cmake: use FindALSA.cmake to find ALSA library

SDL2Config.cmake.in

@@ -30,6 +30,18 @@ if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/SDL2testTargets.cmake")
   set(SDL2_SDL2test_FOUND TRUE)
 endif()
 
+
+include("${CMAKE_CURRENT_LIST_DIR}/sdlfind.cmake")
+
+set(SDL_ALSA @SDL_ALSA@)
+set(SDL_ALSA_SHARED @SDL_ALSA_SHARED@)
+if(SDL_ALSA AND NOT SDL_ALSA_SHARED AND TARGET SDL2::SDL2-static)
+  sdlFindALSA()
+endif()
+unset(SDL_ALSA)
+unset(SDL_ALSA_SHARED)
+
+
 check_required_components(SDL2)
 
 # Create SDL2::SDL2 alias for static-only builds
@@ -62,4 +74,4 @@ if(TARGET SDL2::SDL2main)
   list(INSERT SDL2_STATIC_LIBRARIES 0 SDL2::SDL2main)
 endif()
 
-set(SDL2TEST_LIBRARY SDL2::SDL2test)
+set(SDL2TEST_LIBRARY SDL2::SDL2test)