Revert "Disable LTO temporarily for hwui"

Bug: http://b/62839002
Bug: http://b/74395273

Turn LTO back on for hwui.  The reason for the build breaks were stale profile files in ccache. We'll hold off on updating profile files until this can be fixed.  LTO can be turned back on in the mean time.

This reverts commit 7184e28b.

Change-Id: I051c39a44be6a85682393e7d6e78f49b30bb85e1