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 <david@gibson.dropbear.id.au>