Automatic searching for vcvars.bat and report an error if the file cannot be found.
Automatic searching for vcvars.bat and report an error if the file cannot be found.

This is needed if you do not have VS in your PATH on purpose and makes life easy if you do not have it there by accident.

Review URL: http://codereview.chromium.org/112098

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@17854 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools