cmake: better support of SDL2

Description: Building with SDL2_API=TRUE is incomplete
 SDL_FOUND does not imply SDL2_FOUND
 Use check_libs for detection
 Only include ${SDL_INCLUDE_DIR} when needed
 Use SDL2_LIBRARIES
Author: Miguel A. Colón Vélez

Gregory: add back SDL_BUILDING_LIBRARY

cmake/BuildParameters.cmake

@@ -32,8 +32,6 @@ option(BUILD_REPLAY_LOADERS "Build GS replayer to ease testing (developer option
 option(PACKAGE_MODE "Use this option to ease packaging of PCSX2 (developer/distribution option)")
 option(XDG_STD "Use XDG standard path instead of the standard PCSX2 path")
 option(EXTRA_PLUGINS "Build various 'extra' plugins")
-# FIXME do a proper detection
-set(SDL2_LIBRARY "-lSDL2")
 option(SDL2_API "Use SDL2 on spu2x and onepad")
 option(WX28_API "Force wxWidget 2.8 lib")
 

cmake/SearchForStuff.cmake

@@ -14,9 +14,6 @@ find_package(Gettext) # translation tool
 find_package(Git)
 find_package(JPEG)
 find_package(OpenGL)
-# Tell cmake that we use SDL as a library and not as an application
-set(SDL_BUILDING_LIBRARY TRUE)
-find_package(SDL)
 # The requirement of wxWidgets is checked in SelectPcsx2Plugins module
 # Does not require the module (allow to compile non-wx plugins)
 # Force the unicode build (the variable is only supported on cmake 2.8.3 and above)
@@ -45,6 +42,16 @@ check_lib(GLESV2 GLESv2 GLES3/gl3ext.h) # NOTE: looking for GLESv3, not GLESv2
 check_lib(PORTAUDIO portaudio portaudio.h pa_linux_alsa.h)
 check_lib(SOUNDTOUCH SoundTouch soundtouch/SoundTouch.h)
 
+# Tell cmake that we use SDL as a library and not as an application
+set(SDL_BUILDING_LIBRARY TRUE)
+if(SDL2_API)
+    check_lib(SDL2 SDL2 SDL.h)
+else()
+    # Tell cmake that we use SDL as a library and not as an application
+    set(SDL_BUILDING_LIBRARY TRUE)
+    find_package(SDL)
+endif()
+
 # Note for include_directory: The order is important to avoid a mess between include file from your system and the one of pcsx2
 # If you include first 3rdparty, all 3rdpary include will have a higer priority...
 # If you include first /usr/include, all system include will have a higer priority over the pcsx2 one...
@@ -93,7 +100,7 @@ if(OPENGL_FOUND)
 	include_directories(${OPENGL_INCLUDE_DIR})
 endif()
 
-if(SDL_FOUND)
+if(SDL_FOUND AND NOT SDL2_API)
 	include_directories(${SDL_INCLUDE_DIR})
 endif()
 

cmake/SelectPcsx2Plugins.cmake

@@ -6,8 +6,8 @@ set(msg_dep_pcsx2       "check these libraries -> wxWidgets (>=2.8.10), gtk2 (>=
 set(msg_dep_cdvdiso     "check these libraries -> bzip2 (>=1.0.5), gtk2 (>=2.16)")
 set(msg_dep_zerogs      "check these libraries -> glew (>=1.6), opengl, X11, nvidia-cg-toolkit (>=2.1)")
 set(msg_dep_gsdx        "check these libraries -> opengl, egl, X11")
-set(msg_dep_onepad      "check these libraries -> sdl (==1.2)")
-set(msg_dep_spu2x       "check these libraries -> soundtouch (>=1.5), alsa, portaudio (>=1.9), sdl (==1.2) pcsx2 common libs")
+set(msg_dep_onepad      "check these libraries -> sdl (>=1.2)")
+set(msg_dep_spu2x       "check these libraries -> soundtouch (>=1.5), alsa, portaudio (>=1.9), sdl (>=1.2) pcsx2 common libs")
 set(msg_dep_zerospu2    "check these libraries -> soundtouch (>=1.5), alsa")
 if(GLSL_API)
 	set(msg_dep_zzogl       "check these libraries -> glew (>=1.6), jpeg (>=6.2), opengl, X11, pcsx2 common libs")
@@ -208,7 +208,7 @@ endif()
 #---------------------------------------
 # requires: -SDL
 #---------------------------------------
-if(SDL_FOUND)
+if(SDL_FOUND OR SDL2_FOUND)
 	set(onepad TRUE)
 elseif(NOT EXISTS "${CMAKE_SOURCE_DIR}/plugins/onepad")
 	set(onepad FALSE)
@@ -236,7 +236,7 @@ endif()
 #           -SDL
 #           -common_libs
 #---------------------------------------
-if(ALSA_FOUND AND PORTAUDIO_FOUND AND SOUNDTOUCH_FOUND AND SDL_FOUND AND common_libs)
+if(ALSA_FOUND AND PORTAUDIO_FOUND AND SOUNDTOUCH_FOUND AND (SDL_FOUND OR SDL2_FOUND) AND common_libs)
 	set(spu2-x TRUE)
 elseif(NOT EXISTS "${CMAKE_SOURCE_DIR}/plugins/spu2-x")
 	set(spu2-x FALSE)

plugins/onepad/CMakeLists.txt

@@ -82,7 +82,7 @@ set(onepadWindowsHeaders
 
 if (SDL2_API)
 	set(onepadFinalLibs
-		${SDL2_LIBRARY}
+		${SDL2_LIBRARIES}
 	)
 else()
 	set(onepadFinalLibs

plugins/spu2-x/src/CMakeLists.txt

@@ -122,7 +122,7 @@ include_directories(Linux)
 #     endif(GCC_VERSION VERSION_GREATER 4.7)
 # endif()
 
-if(SDL_FOUND)
+if(SDL_FOUND OR SDL2_FOUND)
     list(APPEND spu2xSources SndOut_SDL.cpp)
     if (SDL2_API)
         set(spu2xFinalFlags
@@ -155,7 +155,7 @@ set(spu2xFinalLibs
 if (SDL2_API)
     set(spu2xFinalLibs
         ${spu2xFinalLibs}
-        ${SDL2_LIBRARY}
+        ${SDL2_LIBRARIES}
     )
 else()
     set(spu2xFinalLibs