Get Mac viewer working with SDL

third_party/libsdl/mac/sdl_mac.gypi

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # Mac specific files and settings for SDL
 
 {
- #TODO what is really necessary here
+
  'link_settings': {
    'libraries': [ 
-     '-lm',
-     '-liconv',
-     '-lobjc',
-     '-lpthread',
      '$(SDKROOT)/System/Library/Frameworks/CoreVideo.framework',
      '$(SDKROOT)/System/Library/Frameworks/Cocoa.framework',
      '$(SDKROOT)/System/Library/Frameworks/Carbon.framework',
      '$(SDKROOT)/System/Library/Frameworks/IOKit.framework',
+     '/usr/lib/libiconv.dylib',
    ],
  },
  'sources': [
    '<(src_dir)/src/SDL_assert.c',
    '<(src_dir)/src/SDL_error.c',
    '<(src_dir)/src/SDL_hints.c',
    '<(src_dir)/src/SDL_log.c',
    '<(src_dir)/src/atomic/SDL_atomic.c',
    '<(src_dir)/src/atomic/SDL_spinlock.c',
    '<(src_dir)/src/audio/SDL_audio.c',
@@ skipping 127 matching lines @@
  'cflags': [
    '-fPIC',
    '-O3',
    '-mmmx',
    '-m3dnow',
    '-msse',
    '-msse2',
    '-fvisibility=hidden',
  ],
 }