Makefile: Improve dependency check error messages

Print out a human-readable error message if a dependency check fails.
For example, if the libbfd library is missing, we print out the
following error message:

  $ make
  Makefile:200: *** No libbfd found, please install binutils-devel or binutils-dev package..  Stop.

Signed-off-by: Pekka Enberg <penberg@kernel.org>