Fix: don't search for SDL, etc., on macOS

CMakeLists.txt

@@ -32,27 +32,27 @@ find_package(ZLIB)
 find_package(LibLZMA)
 find_package(LZO)
 find_package(PNG)
+
 if (NOT WIN32)
-    find_package(SDL2)
-    if (NOT SDL2_FOUND)
-        find_package(SDL)
-    endif( NOT SDL2_FOUND)
     find_package(Allegro)
-    find_package(Fluidsynth)
-    find_package(Freetype)
-    find_package(Fontconfig)
     if (NOT APPLE)
+        find_package(SDL2)
+        if (NOT SDL2_FOUND)
+            find_package(SDL)
+        endif( NOT SDL2_FOUND)
+        find_package(Fluidsynth)
+        find_package(Freetype)
+        find_package(Fontconfig)
         find_package(ICU OPTIONAL_COMPONENTS i18n lx)
+        find_package(XDG_basedir)
+    else (NOT APPLE)
+        find_package(Iconv)
+
+        find_library(AUDIOTOOLBOX_LIBRARY AudioToolbox)
+        find_library(AUDIOUNIT_LIBRARY AudioUnit)
+        find_library(COCOA_LIBRARY Cocoa)
     endif (NOT APPLE)
-    find_package(XDG_basedir)
 endif (NOT WIN32)
-if (APPLE)
-    find_package(Iconv)
-
-    find_library(AUDIOTOOLBOX_LIBRARY AudioToolbox)
-    find_library(AUDIOUNIT_LIBRARY AudioUnit)
-    find_library(COCOA_LIBRARY Cocoa)
-endif (APPLE)
 
 if (MSVC)
     find_package(Editbin REQUIRED)