Update package_source for ninja
Update package_source for ninja

ninja puts generated files in out/Debug/gen instead of out/Debug/obj/gen

BUG=309203
R=agable@chromium.org

Review URL: https://codereview.chromium.org/29213005

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@229491 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build