The Program refactor inadvertantly broken Debug annotations. Fix this
by correctly passing the path to the temporary shader source in the
first "C" string argument to ShCompile, instead of as the first part
of the source string.

BUG=angleproject:1177
TEST=manual testing with MSVS

Change-Id: Ie77bb11b51645a474b542ddd2ae0f391e019e341
Reviewed-on: https://chromium-review.googlesource.com/306210
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>