The :angle-image_util target was a source_set rather than a
static_library(), causing us to link in loadimage.cpp, which
pulled in mathutils.cpp, which contains a static initializer.
Switching :angle_image_util to a static library (which is what GYP
does) solved the problem.

R=rsesek@chromium.org, cwallez@chromium.org
BUG=628052

Change-Id: I63387b3fc9d799c92f7c1b49a1c7c7435e70a951
Reviewed-on: https://chromium-review.googlesource.com/360228Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>