SDL_mixer: cmake: Modernise CMakeLists a bit

From 526af2e0fc3877b59584fa9908fb425616f61c69 Mon Sep 17 00:00:00 2001
From: Charlie Birks <[EMAIL REDACTED]>
Date: Sat, 6 Nov 2021 11:58:28 +0000
Subject: [PATCH] cmake: Modernise CMakeLists a bit

---
 CMakeLists.txt | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0048c7c2..9c7737dc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,39 +40,39 @@ target_sources(SDL2_mixer PRIVATE
         src/codecs/music_nativemidi.c)
 
 if (SUPPORT_WAV)
-    add_definitions(-DMUSIC_WAV)
+    target_compile_definitions(SDL2_mixer PRIVATE -DMUSIC_WAV)
 endif()
 
 if (SUPPORT_FLAC)
-    add_definitions(-DMUSIC_FLAC)
+    target_compile_definitions(SDL2_mixer PRIVATE -DMUSIC_FLAC)
     add_subdirectory(external/flac-1.3.3)
-    include_directories(external/flac-1.3.3/include)
+    target_include_directories(SDL2_mixer PRIVATE external/flac-1.3.3/include)
     target_link_libraries(SDL2_mixer PRIVATE FLAC)
 endif()
 
 if (SUPPORT_OGG)
-    add_definitions(-DMUSIC_OGG -DOGG_USE_TREMOR -DOGG_HEADER=<ivorbisfile.h>)
+    target_compile_definitions(SDL2_mixer PRIVATE -DMUSIC_OGG -DOGG_USE_TREMOR -DOGG_HEADER=<ivorbisfile.h>)
     add_subdirectory(external/libogg-1.3.2)
     add_subdirectory(external/libvorbisidec-1.2.1)
-    include_directories(external/libvorbisidec-1.2.1)
+    target_include_directories(SDL2_mixer PRIVATE external/libvorbisidec-1.2.1)
     target_link_libraries(SDL2_mixer PRIVATE vorbisidec ogg)
 endif()
 
 if (SUPPORT_MP3_MPG123)
-    add_definitions(-DMUSIC_MP3_MPG123)
+    target_compile_definitions(SDL2_mixer PRIVATE -DMUSIC_MP3_MPG123)
     add_subdirectory(external/mpg123-1.25.13)
     target_link_libraries(SDL2_mixer PRIVATE mpg123)
 endif()
 
 if (SUPPORT_MOD_MODPLUG)
-    add_definitions(-DMUSIC_MOD_MODPLUG -DMODPLUG_HEADER=<modplug.h>)
+    target_compile_definitions(SDL2_mixer PRIVATE -DMUSIC_MOD_MODPLUG -DMODPLUG_HEADER=<modplug.h>)
     add_subdirectory(external/libmodplug-0.8.9.0)
-    include_directories(external/libmodplug-0.8.9.0/src)
+    target_include_directories(SDL2_mixer PRIVATE external/libmodplug-0.8.9.0/src)
     target_link_libraries(SDL2_mixer PRIVATE modplug)
 endif()
 
 if (SUPPORT_MID_TIMIDITY)
-    add_definitions(-DMUSIC_MID_TIMIDITY)
+    target_compile_definitions(SDL2_mixer PRIVATE -DMUSIC_MID_TIMIDITY)
     add_subdirectory(src/codecs/timidity)
     target_link_libraries(SDL2_mixer PRIVATE timidity)
 endif()