Landing issue 1751016 for dglazkov:
Landing issue 1751016 for dglazkov:

Add another klugde to relieve Windows-related paths pain.

Without it, DEPTH value on Windows contains backslashes and make MSVS
generators barf.

BUG=152
R=markmentovai
TEST=none


Review URL: http://codereview.chromium.org/1699009
witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp