remove double including of libpng decoder

R=bungeman@google.com

Author: zachr@google.com

Review URL: https://chromiumcodereview.appspot.com/17408002

git-svn-id: http://skia.googlecode.com/svn/trunk@9666 2bbb7eff-a529-9590-31e7-b0007b416f81

gm/gmmain.cpp

@@ -24,6 +24,7 @@
 #include "SkDeferredCanvas.h"
 #include "SkDevice.h"
 #include "SkDrawFilter.h"
+#include "SkForceLinking.h"
 #include "SkGPipe.h"
 #include "SkGraphics.h"
 #include "SkImageDecoder.h"
@@ -37,6 +38,8 @@
 #include "SkTileGridPicture.h"
 #include "SamplePipeControllers.h"
 
+__SK_FORCE_IMAGE_DECODER_LINKING;
+
 #ifdef SK_BUILD_FOR_WIN
     // json includes xlocale which generates warning 4530 because we're compiling without
     // exceptions; see https://code.google.com/p/skia/issues/detail?id=1067

gyp/images.gyp

@@ -106,9 +106,6 @@
           # our code that calls it.
           # See http://code.google.com/p/gyp/wiki/InputFormatReference#Dependent_Settings
           'link_settings': {
-            'sources': [
-              '../src/images/SkImageDecoder_libpng.cpp',
-            ],
             'libraries': [
               '-lgif',
               '-lpng',
@@ -126,9 +123,6 @@
             '../src/images/SkMovie_gif.cpp',
           ],
           'link_settings': {
-            'sources': [
-              '../src/images/SkImageDecoder_libpng.cpp',
-            ],
             'libraries': [
               '-lpng',
               '-lz',