Initialize globals in a separate function instead of a block in the
beginning of main(). This way it works also for globals declared after
main().

BUG=chromium:764036
TEST=angle_end2end_tests

Change-Id: I2fcbb97d046589301287757dc3dde5471172a3f6
Reviewed-on: https://chromium-review.googlesource.com/663158
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>