Build a static bspatch for recovery.

The recovery image must include only static binary. This patch compiles
bspatch as a static binary and installs it in recovery so it can be used
by update_engine_sideload.

Bug: 27178350
TEST=`mmma external/bsdiff` builds the recovery static file.

Change-Id: Ic589b8426a60a101b89b3072be7a868859ccc1e5