Hopeful fix for ninja wrapper on cygwin/mingw
Hopeful fix for ninja wrapper on cygwin/mingw

(ninja.bat is now ninja.exe.)

TBR=maruel@google.com


Review URL: https://chromiumcodereview.appspot.com/10653006

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@143627 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

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