Change the gyp_chromium to build chromium in a symbolic link

If the path of chromium source is a symbolic link,
os.getcwd() returns the real path but __file__ will include
the symbolic link. It causes gyp failures due to the inconsistency.

BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10692086

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@146172 0039d316-1c4b-4281-b951-d872f2087c98

build/gyp_chromium

@@ -13,7 +13,7 @@ import shlex
 import subprocess
 import sys
 
-script_dir = os.path.dirname(__file__)
+script_dir = os.path.dirname(os.path.realpath(__file__))
 chrome_src = os.path.abspath(os.path.join(script_dir, os.pardir))
 
 sys.path.insert(0, os.path.join(chrome_src, 'tools', 'gyp', 'pylib'))