The Makefile didn't build libbspatch and libbsdiff. This patch includes
those libraries in the Makefile and moves the header files exposed by
those to an include/bsdiff subdirectory following the Android
convention so calling program can include "bsdiff/bspatch.h" avoiding
any collision with other libraries.

The Android.mk is updated to export the new include path while keeping
the old style until calling programs are updated.

The new Makefile allows Chromium OS to build the new libraries.

Bug: None
Test: FEATURES=test emerge-link bsdiff; sudo emerge bsdiff
Test: mmma external/bsdiff

Change-Id: I2ea9251eb224e9418fe236e4c4c9c5621853f590