The Android blob cache has a limit of 2MB, so ANGLE should compress the
Program binaries that are saved into it to maximize its effectiveness.

ANGLE will gzip the program binaries before being stored in the blob
cache and then uncompress them when retrieved. Using gzip, the binaries
are compressed to ~25% of their size when running the T-Rex benchmark.

Some examples (in bytes):

Uncompressed: 20193, Compressed: 4455
Uncompressed:  8767, Compressed: 2369
Uncompressed: 11144, Compressed: 2927

This doesn't appear to affect the T-Rex benchmark since all of the
programs are loaded/decompressed as part of the benchmark
initialization, and the programs are small enough to all fit in the
blob cache without compression.

Bug: b/155184635
Test: T-Rex, CQ
Change-Id: Ie6a101c32ab5fd49baae1cb7aecdd26a934e15af
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2227529Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>