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
diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index eb87181..d44c560 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -185,7 +185,7 @@
 #define SK_MaxU16   0xFFFF
 #define SK_MinU16   0
 #define SK_MaxS32   0x7FFFFFFF
-#define SK_MinS32   0x80000001
+#define SK_MinS32   -SK_MaxS32
 #define SK_MaxU32   0xFFFFFFFF
 #define SK_MinU32   0
 #define SK_NaN32    0x80000000