[premake] Cleanup

src/xenia/apu/nop/premake5.lua

@@ -10,6 +10,4 @@ project("xenia-apu-nop")
     "xenia-base",
     "xenia-apu",
   })
-  defines({
-  })
   local_platform_files()

src/xenia/apu/premake5.lua

@@ -12,8 +12,6 @@ project("xenia-apu")
     "libavformat",
     "xenia-base",
   })
-  defines({
-  })
   includedirs({
     project_root.."/third_party/FFmpeg/",
   })

src/xenia/apu/sdl/premake5.lua

@@ -12,7 +12,5 @@ project("xenia-apu-sdl")
     "xenia-helper-sdl",
     "SDL2",
   })
-  defines({
-  })
   local_platform_files()
   sdl2_include()

src/xenia/apu/xaudio2/premake5.lua

@@ -10,6 +10,4 @@ project("xenia-apu-xaudio2")
     "xenia-base",
     "xenia-apu",
   })
-  defines({
-  })
   local_platform_files()