Enable both static and dynamically linked libpng

gyp/codec.gyp

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # GYP file for codec project.
 {
   'targets': [
     {
       'target_name': 'codec',
       'product_name': 'skia_codec',
       'type': 'static_library',
       'standalone_static_library': 1,
       'dependencies': [
         'core.gyp:*',
-        'libpng.gyp:libpng',
+        'libpng.gyp:libpng_static',

[djsollen, 2015/03/26 16:39:12]

need to make this conditional so that the framework build still used the old
library until we can prove the overhead of the newer library is worth it.

[scroggo, 2015/03/26 17:19:02]

I'm not sure what you mean by this comment. Is this a TODO? It seems like this
won't build on the framework right now, since we don't have
third_party/externals.

[djsollen, 2015/04/01 15:12:43]

This is addressed in my next patch.

       ],
       'cflags':[
         # FIXME: This gets around a longjmp warning. See
         # http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-GCC-x86_64-Release-Trybot/builds/113/steps/build%20most/logs/stdio
         '-Wno-clobbered',
       ],
       'include_dirs': [
         '../include/codec',
         '../src/codec',
         '../src/core',
       ],
       'sources': [
         '../src/codec/SkCodec.cpp',
         '../src/codec/SkCodec_libbmp.cpp',
         '../src/codec/SkCodec_libico.cpp',
         '../src/codec/SkCodec_libpng.cpp',
         '../src/codec/SkMaskSwizzler.cpp',
         '../src/codec/SkMasks.cpp',
         '../src/codec/SkSwizzler.cpp',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           '../include/codec',
         ],
       },
     },
   ],
 }