roll gyp 1841:1842.

r1841: remove unreferenced gyp_dummy.c
r1842: De-hardcode link concurrency for Windows.

R=scottmg@chromium.org
BUG=

Review URL: https://codereview.chromium.org/143703002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245971 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245972 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245972