Prepare skia for shared library build on android

This reapplies revision 9378 after the buildbot has been updated.

R=borenet@google.com, djsollen@google.com

Review URL: https://codereview.chromium.org/15855006

git-svn-id: http://skia.googlecode.com/svn/trunk@9395 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gyp/common_variables.gypi b/gyp/common_variables.gypi
index 4f9f542..ac937bd 100644
--- a/gyp/common_variables.gypi
+++ b/gyp/common_variables.gypi
@@ -90,6 +90,7 @@
       'skia_osx_sdkroot%': '',
       'skia_profile_enabled%': 0,
       'skia_win_debuggers_path%': '',
+      'skia_shared_lib%': 0,
     },
 
     'conditions': [
@@ -121,6 +122,7 @@
     'skia_gpu%': '<(skia_gpu)',
     'skia_osx_sdkroot%': '<(skia_osx_sdkroot)',
     'skia_profile_enabled%': '<(skia_profile_enabled)',
+    'skia_shared_lib%': '<(skia_shared_lib)',
     'skia_static_initializers%': '<(skia_static_initializers)',
     'ios_sdk_version%': '6.0',
     'skia_win_debuggers_path%': '<(skia_win_debuggers_path)',