Fix incorrect hashing on built-in interface block fields This patch intends to fix an error in translating built-in interface block fields. Any field of a built-in interface block should be kept and cannot be hashed. This patch can fix a bug in handling the interface block gl_in when we try to output the translated geometry shader string. BUG=angleproject:1941 TEST=angle_unittest Change-Id: Iebfba4b6a30c8942ed0f66131ad30d12ad96c62a Reviewed-on: https://chromium-review.googlesource.com/719454 Commit-Queue: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org>