gensupport.c: New file.

	* gensupport.c: New file.
	* gensupport.h: New file.
	* Makefile.in (HOST_RTL): Depend on gensupport.
	(gensupport.o) New rule.
	* genattr.c: Use gensupport for reading .md files.
	* genattrtab.c: Ditto.
	* gencodes.c: Ditto.
	* genconfig.c: Ditto.
	* genemit.c: Ditto.
	* genextract.c: Ditto.
	* genflags.c: Ditto.
	* genopinit.c: Ditto.
	* genoutput.c: Ditto.
	* genpeep.c: Ditto.
	* genrecog.c: Ditto.
	* rtl.def (define_insn_and_split): New DEF_RTL_EXPR.
	* md.texi (Insn Splitting): Document define_insn_and_split.

From-SVN: r33633