Finish cmake stuff for Switch build

* SDL2 for OpenAL not needed anymore
* Add re3_platform_target function and use that instead of manually building NRO

CMakeLists.txt

@@ -4,18 +4,25 @@ set(EXECUTABLE re3)
 set(PROJECT RE3)
 
 project(${EXECUTABLE} C CXX)
+set(${PROJECT}_AUTHOR "${PROJECT} Team")
 list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 
 include(GetGitRevisionDescription)
 get_git_head_revision(GIT_REFSPEC GIT_SHA1 "ALLOW_LOOKING_ABOVE_CMAKE_SOURCE_DIR")
 message(STATUS "Building ${CMAKE_PROJECT_NAME} GIT SHA1: ${GIT_SHA1}")
 
-if(WIN32)
-    set(${PROJECT}_AUDIOS "OAL" "MSS")
-elseif(NINTENDO_SWITCH)
+if(NINTENDO_SWITCH)
     list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake/nx")
     include(NXFunctions)
-    set(${PROJECT}_AUDIOS "OAL")
+endif()
+
+if(NOT COMMAND re3_platform_target)
+    function(re3_platform_target)
+    endfunction()
+endif()
+
+if(WIN32)
+    set(${PROJECT}_AUDIOS "OAL" "MSS")
 else()
     set(${PROJECT}_AUDIOS "OAL")
 endif()