The newly added capability constants are handled in the corresponding
glGet functions. Also, getBooleani_v has been added.

BUG=angleproject:1442

TEST=angle_deqp_gtest_gles31_tests
--gtest_filter=*functional_state_query_integer_max_*
TEST=angle_deqp_gtest_gles31_tests
--gtest_filter=*state_query_indexed_max_compute_work_group_size*
TEST=angle_unittests
TEST=angle_end2end_tests

Change-Id: I846e006307563ae81d8b6c62cf261417e15186c7
Reviewed-on: https://chromium-review.googlesource.com/362270Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>