Add CMake PLATFORM option for Desktop SDL (#3809)

CMakeOptions.txt

@@ -2,7 +2,7 @@
 include(CMakeDependentOption)
 include(EnumOption)
 
-enum_option(PLATFORM "Desktop;Web;Android;Raspberry Pi;DRM" "Platform to build for.")
+enum_option(PLATFORM "Desktop;Web;Android;Raspberry Pi;DRM;SDL" "Platform to build for.")
 
 enum_option(OPENGL_VERSION "OFF;4.3;3.3;2.1;1.1;ES 2.0;ES 3.0" "Force a specific OpenGL Version?")
 

cmake/LibraryConfigurations.cmake

@@ -91,6 +91,11 @@ elseif ("${PLATFORM}" MATCHES "DRM")
     endif ()
     set(LIBS_PRIVATE ${GLESV2} ${EGL} ${DRM} ${GBM} atomic pthread m dl)
 
+elseif ("${PLATFORM}" MATCHES "SDL")
+    find_package(SDL2 REQUIRED)
+    set(PLATFORM_CPP "PLATFORM_DESKTOP_SDL")
+    set(LIBS_PRIVATE SDL2::SDL2)
+
 endif ()
 
 if (NOT ${OPENGL_VERSION} MATCHES "OFF")