This patch enables that the interface block information can be correctly
collected in API side for std430 layout. So we can get right offset value when
we use glGetProgramResourceiv to query.

BUG=angleproject:1920

Change-Id: Ib936f6e25936c07c5bbc29f6b567d282a0f257c2
Reviewed-on: https://chromium-review.googlesource.com/c/1345891Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jiajia Qin <jiajia.qin@intel.com>