dtc: Improve and better integrate dtc and libfdt Makefiles

This patch substantially revamps the dtc Makefiles, in particular
better integrating the Makefile for dtc proper with the Makefiles
imported from libfdt for libfdt and the shared testsuite.  Notable
changes:
	- No recursive make calls.  Instead subsidiary Makefiles are
included into the top-level Makefile so we get a complete dependency
information.
	- Common pattern rules, CFLAGS etc. shared between dtc, libfdt
and testsuite, rather than separate copies.
	- Vaguely Kbuild-like non-verbose mode used by default, which
makes warnings more prominent.
	- libfdt Makefile consists only of variable definitions and
helper rules, to make it more easily embeddable into other Makefile
systems.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
5 files changed