cmake: output libSDL2-2.0.0.dylib like autotools, not libSDL2-2.0.dylib.

libSDL2-2.0.dylib is now installed as a symlink to libSDL2-2.0.0.dylib :

$ ls -l *.dylib
-rwxr-xr-x. 1 ozkan ozkan 1755488 Sep 23 23:53 libSDL2-2.0.0.dylib
lrwxrwxrwx. 1 ozkan ozkan      19 Sep 23 23:53 libSDL2-2.0.dylib -> libSDL2-2.0.0.dylib
lrwxrwxrwx. 1 ozkan ozkan      17 Sep 23 23:53 libSDL2.dylib -> libSDL2-2.0.dylib

Reference issue: https://github.com/libsdl-org/sdl12-compat/issues/217

CMakeLists.txt

@@ -3078,8 +3078,10 @@ if(SDL_SHARED)
   add_library(SDL2::SDL2 ALIAS SDL2)
   set_target_properties(SDL2 PROPERTIES POSITION_INDEPENDENT_CODE TRUE)
   if(APPLE)
+    # FIXME: Remove SOVERSION in SDL3
     set_target_properties(SDL2 PROPERTIES
       MACOSX_RPATH 1
+      SOVERSION 0
       OUTPUT_NAME "SDL2-${LT_RELEASE}")
   elseif(UNIX AND NOT ANDROID)
     set_target_properties(SDL2 PROPERTIES