Apple M1: Update AutoUpdate PlatformID

Adds a new PlatformID for universal builds. This will allow single architecture
builds to be updated through the single architecture path, and universal builds
to be updated with universal builds.

BuildMacOSUniversalBinary.py

@@ -271,6 +271,8 @@ def build(config):
         subprocess.check_call([
                 "cmake", "../../", "-G", config["generator"],
                 "-DCMAKE_BUILD_TYPE=" + config["build_type"],
+                '-DCMAKE_CXX_FLAGS="-DMACOS_UNIVERSAL_BUILD=1"',
+                '-DCMAKE_C_FLAGS="-DMACOS_UNIVERSAL_BUILD=1"',
                 # System name needs to be specified for CMake to use
                 # the specified CMAKE_SYSTEM_PROCESSOR
                 "-DCMAKE_SYSTEM_NAME=Darwin",

Source/Core/UICommon/AutoUpdate.cpp

@@ -140,7 +140,11 @@ static std::string GetPlatformID()
 #if defined _WIN32
   return "win";
 #elif defined __APPLE__
+#if defined(MACOS_UNIVERSAL_BUILD)
+  return "macos-universal";
+#else
   return "macos";
+#endif
 #else
   return "unknown";
 #endif