Add "Optimize_for_size" build property

Projects with this property will be aggresively optimized for size. This
is useful for large binaries that are rarely executed and performance
insensitive (e.g. debugging tools, deprecated libraries).

This changeset reduces total system native binary size by 1.1%.

Test: presubmit
Bug: 342090838
Change-Id: I46a1db0c44e2e7d482b14eca1299f8ad48661d2d