Fix ugly typo in r14391.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/14425006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14392 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

build/gyp_v8

@@ -162,6 +162,6 @@ if __name__ == '__main__':
 
   # Generate for the architectures supported on the given platform.
   gyp_args = list(args)
-  if platform.system() == 'linux':
+  if platform.system() == 'Linux':
     gyp_args.append('--generator-output=out')
   run_gyp(gyp_args)