fixup pandora compilation with SDL < 1.2.12

This was checked to compile (but not link of course) on my system,
using cmake with pandora enabled, and pointed to the SDL_mixer
1.2.0 header. (the master version, not this cherry-pick)

I also essentially backported this commit:

cef5e2e

which checks reduces the CMake version requirement for pandora

CMakeLists.txt

@@ -545,7 +545,12 @@ if(ENABLE_TOOLS OR ENABLE_GAME OR ENABLE_TESTS)
 	find_package( SDL_image 1.2 REQUIRED )
 endif(ENABLE_TOOLS OR ENABLE_GAME OR ENABLE_TESTS)
 if(ENABLE_GAME OR ENABLE_TESTS)
-	find_package( SDL_mixer 1.2.12 REQUIRED )
+	if(ENABLE_PANDORA)
+		find_package( SDL_mixer 1.2.0 REQUIRED )
+	else(ENABLE_PANDORA)
+		find_package( SDL_mixer 1.2.12 REQUIRED )
+	endif(ENABLE_PANDORA)
+
 	find_package( SDL_ttf 2.0.8 REQUIRED )
 
 	if(NOT MSVC)

src/sound.cpp

@@ -489,8 +489,14 @@ static void play_new_music()
 	std::map<std::string,Mix_Music*>::const_iterator itor = music_cache.find(filename);
 	if(itor == music_cache.end()) {
 		LOG_AUDIO << "attempting to insert track '" << filename << "' into cache\n";
+
+#ifndef PANDORA
 		SDL_RWops *rwops = filesystem::load_RWops(filename);
 		Mix_Music* const music = Mix_LoadMUSType_RW(rwops, MUS_NONE, true); // SDL takes ownership of rwops
+#else
+		Mix_Music* const music = Mix_LoadMUS(filename.c_str());
+#endif
+
 		if(music == NULL) {
 			ERR_AUDIO << "Could not load music file '" << filename << "': "
 					  << Mix_GetError() << "\n";
@@ -712,8 +718,12 @@ static Mix_Chunk* load_chunk(const std::string& file, channel_group group)
 		std::string const &filename = filesystem::get_binary_file_location("sounds", file);
 
 		if (!filename.empty()) {
+#ifndef PANDORA
 			SDL_RWops *rwops = filesystem::load_RWops(filename);
 			temp_chunk.set_data(Mix_LoadWAV_RW(rwops, true)); // SDL takes ownership of rwops
+#else
+			temp_chunk.set_data(Mix_LoadWAV(filename.c_str()));
+#endif
 		} else {
 			ERR_AUDIO << "Could not load sound file '" << file << "'.\n";
 			throw chunk_load_exception();