core/Makefile: Allow specification of file locations
core/Makefile: Allow specification of file locations

If multiple build targets use a common recovery.fstab or system.prop,
this allows them to live in a centralized location and not be copied
or symlinked to the device directories.

Change-Id: I7aeb31ed9dc9b43a5e2c9e46fe582b10cba71b24
Signed-off-by: Andrew Boie <aab045b28152628be6af0e556050d0381fd0a34d@intel.com>

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build