cmake: Fix bug #5361.

src/joystick/*.c wasn't unconditionally added to source list even though
joystick is an SDL subsystem. Also removed the `SDL_JOYSTICK AND NOT APPLE`
condition from src/joystick/dummy/*.c source addition: the OSX unresolved
symbols issue, if it really is there, should be fixed separately.

Fixes https://github.com/libsdl-org/SDL/issues/5361, i.e. build failures
when SDL_JOYSTICK and SDL_HAPTIC are disabled.

CMakeLists.txt

@@ -471,6 +471,7 @@ file(GLOB SOURCE_FILES
   ${SDL2_SOURCE_DIR}/src/dynapi/*.c
   ${SDL2_SOURCE_DIR}/src/events/*.c
   ${SDL2_SOURCE_DIR}/src/file/*.c
+  ${SDL2_SOURCE_DIR}/src/joystick/*.c
   ${SDL2_SOURCE_DIR}/src/haptic/*.c
   ${SDL2_SOURCE_DIR}/src/hidapi/*.c
   ${SDL2_SOURCE_DIR}/src/libm/*.c
@@ -961,10 +962,6 @@ foreach(_SUB ${SDL_SUBSYSTEMS})
     set(SDL_${_OPT}_DISABLED 1)
   endif()
 endforeach()
-if(SDL_JOYSTICK)
-  file(GLOB JOYSTICK_SOURCES ${SDL2_SOURCE_DIR}/src/joystick/*.c)
-  set(SOURCE_FILES ${SOURCE_FILES} ${JOYSTICK_SOURCES})
-endif()
 if(SDL_HAPTIC)
   if(NOT SDL_JOYSTICK)
     # Haptic requires some private functions from the joystick subsystem.
@@ -2558,10 +2555,8 @@ if(NOT HAVE_SDL_VIDEO)
 endif()
 if(NOT HAVE_SDL_JOYSTICK)
   set(SDL_JOYSTICK_DUMMY 1)
-  if(SDL_JOYSTICK AND NOT APPLE) # results in unresolved symbols on OSX
-    file(GLOB JOYSTICK_SOURCES ${SDL2_SOURCE_DIR}/src/joystick/dummy/*.c)
-    set(SOURCE_FILES ${SOURCE_FILES} ${JOYSTICK_SOURCES})
-  endif()
+  file(GLOB JOYSTICK_SOURCES ${SDL2_SOURCE_DIR}/src/joystick/dummy/*.c)
+  set(SOURCE_FILES ${SOURCE_FILES} ${JOYSTICK_SOURCES})
 endif()
 if(NOT HAVE_SDL_HAPTIC)
   set(SDL_HAPTIC_DUMMY 1)