don't assume bash is installed
don't assume bash is installed

On systems like OpenBSD bash isn't available by default, this removes the hard
coded path.

Review URL: https://codereview.chromium.org/23460007/
Patch from qbit <deftly@gmail.com>!

old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google