The Intel Mesa driver considers the #pragma directive to be a
non-preprocessor token which makes shaders fail compilation.

The relevant blurb from the spec is: "the extension directives
must occur before any non-preprocessor tokens"

BUG=627417

Change-Id: Ic22cff49a9f9c1fe5d140302581ca7b36688732c
Reviewed-on: https://chromium-review.googlesource.com/359621Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>