At the beginning of Program::defineUniformBlock, getUniformBlockSize will call
getUniformBlockIndex on MacOS to check if the block is an active block with
giving blockName. However, it didn't distinguish array and non-array situations
and unified to use interfaceBlock.name as the blockName to call
getUniformBlockIndex. It would result that INVALID_INDEX was returned when
it's a block array. For example, using 'blockName' not 'blockName[0]'.

In OpenGL 4.3 spec, section 7.3.1, there are following descriptions:
If name exactly matches the name string of one of the active resources for
programInterface, the index of the matched resource is returned. Additionally, if
name would exactly match the name string of an active resource if "[0]" were
appended to name, the index of the matched resource is returned. Otherwise, name
is considered not to be the name of an active resource, and INVALID_INDEX is
returned.

So, for array block case, we use blockName appending [0] to check the activity.

BUG=angleproject:1543

Change-Id: I8189b62066b779f7d392a7dba1cf5cb02a31936d
Reviewed-on: https://chromium-review.googlesource.com/405830Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>