Added 64 bit number support in the build gles2 command buffer script.

All members in the command buffer structures need to be 32 bit aligned,
for this reason 64 bit numbers were not supported. I have added
functionality to convert 64 bit numbers into 2 separate fields. This
was previously done manually in some commands (glClientWaitSync,
glWaitSync) and broken in other commands that used 64 bit arguments
(glInsertFenceSyncCHROMIUM, glWaitSyncTokenCHROMIUM).

R=zmo@chromium.org
BUG=514815

Review URL: https://codereview.chromium.org/1528163002

Cr-Commit-Position: refs/heads/master@{#365407}
8 files changed