iOS support work in progress

iOS support work in progress

include/core/SkTypes.h
- address unsigned warning

include/core/SkInstCnt.h
src/core/SkInstCnt.cpp
gyp/common.gypi
- always define SK_ENABLE_INST_COUNT for debug builds

src/views/mac/SkNSView.mm
- only call glClear if there is a GL context

src/ports/SkImageDecoder_CG.cpp
- fix iOS hack by using proper include

gyp/opts.gyp
- exclude more ARM files from iOS for now (see issue 900)

gyp/common_conditions.gypi
- add release, more ios specific common settings

gyp/bench.gyp
- add iOS condition

gyp/SampleApp.gyp
- remove precompiled header, hardcoded SDK path
- add more frameworks

gyp/debugger.gyp
- fix syntax error
- add iOS/Android condition

gyp/core.gyp
- remove hardcoded SDK path, add more frameworks

gyp/common_variables.gypi
- add ios SDK path
- add ios SDK version

gyp/iOSSampleApp.gyp
- remove obsolete project

gyp/zlib.gyp
- add ios library path
Review URL: https://codereview.appspot.com/6551070

git-svn-id: http://skia.googlecode.com/svn/trunk@5649 2bbb7eff-a529-9590-31e7-b0007b416f81