Speculative fix for mt.exe general error c101008a (The parameter is incorrect).

The fix makes sure that the target manifest file is deleted before running mt.exe.

BUG=173052

Review URL: https://codereview.chromium.org/12192023


git-svn-id: http://gyp.googlecode.com/svn/trunk@1567 78cadc50-ecff-11dd-a971-7dbc132099af
Reverting accidental change to test/lib/TestGyp.py


git-svn-id: http://gyp.googlecode.com/svn/trunk@1568 78cadc50-ecff-11dd-a971-7dbc132099af