Re: dtc: Refactor Makefiles (v2)

So, like, the other day David Gibson mumbled:

Here's a corrected version.

dtc: Refactor Makefiles

This patch makes a number of Makefile cleanups and improvements:
	- We use more generic rules to invoke flex and bison, which is
useful for some of the other changes.
	- We use the name dtc-lexer.lex.c for the flex output, instead
of the default lex.yy.c.  That means less potential for confusion if
dtc is embedded into other projects (e.g. the kernel).
	- We separate out a Makefile.dtc designed for embedding into
other projects, analagous to Makefile.libfdt.
	- Makefile.libfdt is cleaned up to be more useful based on
some actual trial runs of embedding libfdt in the kernel bootwrapper.
	- Versioning related rules and variables are collected into
one place in the Makefile.

Signed-off-by: David Gibson <redacted>

Applied.

Thanks,
jdl