Pull SDKROOT into a gyp variable, so it can be locally overridden. This

allows building on Lion or Mountain Lion using XCode 4.4.

http://codereview.appspot.com/6553044/



git-svn-id: http://skia.googlecode.com/svn/trunk@5607 2bbb7eff-a529-9590-31e7-b0007b416f81

gyp/common_conditions.gypi

@@ -181,7 +181,7 @@
         'xcode_settings': {
           'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO',
           'SYMROOT': '<(DEPTH)/xcodebuild',
-          'SDKROOT': 'macosx10.6',
+          'SDKROOT': '<(skia_osx_sdkroot)',
 # trying to get this to work, but it needs clang I think...
 #          'WARNING_CFLAGS': '-Wexit-time-destructors',
           'CLANG_WARN_CXX0X_EXTENSIONS': 'NO',

gyp/common_variables.gypi

@@ -78,6 +78,7 @@
       'android_make_apk%': 1,
       'skia_nacl%': 0,
       'skia_gpu%': 1,
+      'skia_osx_sdkroot%': 'macosx10.6',
     },
 
     # Re-define all variables defined within the level-2 'variables' dict,
@@ -94,6 +95,7 @@
     'android_make_apk%': '<(android_make_apk)',
     'skia_nacl%': '<(skia_nacl)',
     'skia_gpu%': '<(skia_gpu)',
+    'skia_osx_sdkroot%': '<(skia_osx_sdkroot)',
     'skia_static_initializers%': '<(skia_static_initializers)',
 
     # These are referenced by our .gypi files that list files (e.g. core.gypi)