allow gyp_skia to be run from any directory.

R=epoger@google.com

Author: halcanary@google.com

Review URL: https://codereview.chromium.org/240383003

git-svn-id: http://skia.googlecode.com/svn/trunk@14239 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gyp_skia b/gyp_skia
index 7a45026..20bfd79 100755
--- a/gyp_skia
+++ b/gyp_skia
@@ -15,7 +15,7 @@
 import shlex
 import sys
 
-script_dir = os.path.dirname(__file__)
+script_dir = os.path.abspath(os.path.dirname(__file__))
 
 # Directory within which we can find the gyp source.
 gyp_source_dir = os.path.join(script_dir, 'third_party', 'externals', 'gyp')