Remove another now-unnecessary msvs_cygwin_shell:1

Was another workaround for escaping arguments, no longer needed in
ninja-only world.

R=thakis@chromium.org
BUG=123026
TEST=ninja -C out\Debug mini_installer

Review URL: https://codereview.chromium.org/130893006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247650 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247650