Add manifest for building as a flatpak

includes the following:

- org.DolphinEmu.dolphin-emu.metainfo.xml.in this file contains general
  information and metadata that is used by most linux based app stores
  (kde discover, gnome software, flathub.org, etc) to showcase dolphin.
- fill_release_node.sh a script to automatically fill in the release
  information in the metainfo file when building the flatpak.
- SDL2.json manifest to build the vendored version of SDL from the
  Exports directory, it's only temporarily needed until the kde runtime
  is updated with the current SDL2 version and should be deleted after.
- org.DolphinEmu.dolphin-emu.yml the manifest itself.

Flatpak/SDL2/SDL2.json

@@ -0,0 +1,22 @@
+{
+  "name": "SDL2",
+  "buildsystem": "autotools",
+  "config-opts": ["--disable-static"],
+  "sources": [
+    {
+      "type": "dir",
+      "path": "../../Externals/SDL/SDL"
+    }
+  ],
+  "cleanup": [ "/bin/sdl2-config",
+               "/include",
+               "/lib/libSDL2.la",
+               "/lib/libSDL2main.a",
+               "/lib/libSDL2main.la",
+               "/lib/libSDL2_test.a",
+               "/lib/libSDL2_test.la",
+               "/lib/cmake",
+               "/share/aclocal",
+               "/lib/pkgconfig"]
+}
+

Flatpak/fill_release_node.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+
+DATE=$(git log -1 --pretty=%cd --date=iso8601 --date=format:'%Y-%m-%d')
+sed -i -e "s/@DATE_PLACEHOLDER/${DATE}/" org.DolphinEmu.dolphin-emu.metainfo.xml
+VERSION=$(git describe --tags)
+sed -i -e "s/@VERSION_PLACEHOLDER/${VERSION}/" org.DolphinEmu.dolphin-emu.metainfo.xml
+
+

Flatpak/org.DolphinEmu.dolphin-emu.metainfo.xml.in

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Copyright 2016 Jeremy Newton -->
+<component type="desktop-application">
+  <id>org.DolphinEmu.dolphin-emu</id>
+  <name>Dolphin Emulator</name>
+  <developer id="org.dolphin-emu">
+    <name>Dolphin Emulator Project</name>
+  </developer>
+  <summary>GameCube / Wii</summary>
+  <metadata_license>CC-BY-SA-3.0</metadata_license>
+  <project_license>GPL-2.0+</project_license>
+  <content_rating type="oars-1.0"/>
+  <!-- Descriptions taken from Dolphin Homepage -->
+  <description><p>Dolphin is an emulator for two recent Nintendo video game consoles: the GameCube and the Wii. It allows PC gamers to enjoy games for these two consoles in full HD (1080p) with several enhancements: compatibility with all PC controllers, turbo speed, networked multiplayer, and even more!</p></description>
+  <screenshots>
+    <screenshot type="default">
+      <caption>Dolphin's main window</caption>
+      <image type="source">http://dolphin-emu.org/m/user/flatpak/screenshot_1.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>In-game</caption>
+      <image type="source">http://dolphin-emu.org/m/user/flatpak/screenshot_2.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>Graphics configuration</caption>
+      <image type="source">http://dolphin-emu.org/m/user/flatpak/screenshot_3.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>Controller configuration</caption>
+      <image type="source">http://dolphin-emu.org/m/user/flatpak/screenshot_4.png</image>
+    </screenshot>
+  </screenshots>
+  <launchable type="desktop-id">dolphin-emu.desktop</launchable>
+  <provides>
+    <binary>dolphin-emu</binary>
+    <id>dolphin-emu.desktop</id>
+  </provides>
+  <releases>
+    <release version="@VERSION_PLACEHOLDER" date="@DATE_PLACEHOLDER"/>
+  </releases>
+  <url type="homepage">https://dolphin-emu.org</url>
+  <url type="bugtracker">https://bugs.dolphin-emu.org/projects/emulator/issues</url>
+  <url type="faq">https://dolphin-emu.org/docs/faq/</url>
+  <url type="help">https://dolphin-emu.org/docs/guides/</url>
+  <url type="translate">https://www.transifex.com/projects/p/dolphin-emu</url>
+  <url type="contact">https://dolphin-emu.org/docs/faq/#ive-got-idea-make-dolphin-better-how-should-i-tell</url>
+  <url type="vcs-browser">https://github.com/dolphin-emu/dolphin</url>
+  <url type="contribute">https://github.com/dolphin-emu/dolphin/blob/master/Contributing.md</url>
+</component>

Flatpak/org.DolphinEmu.dolphin-emu.yml

@@ -0,0 +1,83 @@
+app-id: org.DolphinEmu.dolphin-emu
+runtime: org.kde.Platform
+runtime-version: '6.7'
+sdk: org.kde.Sdk
+command: dolphin-emu-wrapper
+rename-desktop-file: dolphin-emu.desktop
+rename-icon: dolphin-emu
+finish-args:
+  - --device=all
+  - --socket=pulseaudio
+  # dolphin doesn't work on wayland (only the ui does), if a user were to set
+  # this env variable globally to wayland then games wouldn't work. 
+  # we overwrite the setting and force xcb to prevent this from happening.
+  - --env=QT_QPA_PLATFORM=xcb
+  - --socket=x11
+  - --share=network
+  - --share=ipc
+  # required for the emulated bluetooth adapter feature to work.
+  - --allow=bluetooth
+  - --filesystem=xdg-run/app/com.discordapp.Discord:create
+  - --talk-name=org.freedesktop.ScreenSaver
+  # required for Gamescope on Steam Deck
+  - --filesystem=xdg-run/gamescope-0:ro
+modules:
+  # enables motion controls on non-wii controllers (switch, ps4, etc)
+  # requires a udev rule enabling Motion Sensors access
+  - name: libevdev
+    buildsystem: meson
+    config-opts:
+      - -Dtests=disabled
+      - -Ddocumentation=disabled
+    sources:
+      - type: archive
+        url: https://www.freedesktop.org/software/libevdev/libevdev-1.13.2.tar.xz
+        sha256: 3eca86a6ce55b81d5bce910637fc451c8bbe373b1f9698f375c7f1ad0de3ac48
+        x-checker-data:
+          type: anitya
+          project-id: 20540
+          stable-only: true
+          url-template: https://www.freedesktop.org/software/libevdev/libevdev-$version.tar.xz
+
+  # needed for screensaver inhibition
+  - name: xdg-screensaver-shim
+    buildsystem: meson
+    sources:
+      - type: archive
+        url: https://github.com/Unrud/xdg-screensaver-shim/archive/0.0.2.tar.gz
+        sha256: 0ed2a69fe6ee6cbffd2fe16f85116db737f17fb1e79bfb812d893cf15c728399
+
+  # build the vendored SDL2 from Externals until the runtime gets 2.30.6
+  - SDL2/SDL2.json
+
+  - name: dolphin-emu
+    buildsystem: cmake-ninja
+    config-opts:
+      - -DCMAKE_BUILD_TYPE=Release
+      - -DENABLE_ALSA=OFF
+      - -DENABLE_SDL=ON
+      - -DENABLE_EVDEV=ON
+      - -DDISTRIBUTOR=dolphin-emu.org
+    cleanup:
+      - /share/man
+    post-install:
+      - install -D -t ${FLATPAK_DEST}/bin/ dolphin-emu-wrapper
+      - "${FLATPAK_BUILDER_BUILDDIR}/Flatpak/fill_release_node.sh"
+      - install -Dm644 -t ${FLATPAK_DEST}/share/metainfo/ org.DolphinEmu.dolphin-emu.metainfo.xml
+      - desktop-file-edit --set-key=Exec --set-value='/app/bin/dolphin-emu-wrapper'
+        /app/share/applications/dolphin-emu.desktop
+    sources:
+      - type: dir
+        path: ..
+      - type: file
+        path: org.DolphinEmu.dolphin-emu.metainfo.xml.in
+        dest-filename: org.DolphinEmu.dolphin-emu.metainfo.xml
+      - type: script
+        commands:
+          - |
+            for i in {0..9}; do
+              test -S $XDG_RUNTIME_DIR/discord-ipc-$i ||
+                ln -sf {app/com.discordapp.Discord,$XDG_RUNTIME_DIR}/discord-ipc-$i;
+            done
+            dolphin-emu "$@"
+        dest-filename: dolphin-emu-wrapper