* Makefile.in (RUN_GEN, VALGRIND_DRIVER_DEFINES): New variables.
	(DRIVER_DEFINES): Add $(VALGRIND_DRIVER_DEFINES).
	(executing gencheck, genconfigs, genconditions, genflags,
	gencodes, genconstants, genemit, genrecog, genopinit, genextract,
	genpeep, genattr, genattrtab, genoutput, gengenrtl, genpreds,
	gengtype, genprotos): Prepend $(RUN_GEN).
	* configure.in: Move host compiler tests before --enable-checking
	tests.
	(--enable-checking=valgrind): New.
	* config.in, configure: Regenerate.
	* cppfiles.c [!ENABLE_VALGRIND_CHECKING] (VALGRIND_DISCARD):
	Define as empty.
	(read_include_file): When doing the mmap+1 trick,
	valgrind-annotate the byte after the mmap:ed area as readable.
	(purge_cache): Remove above annotation.
	* gcc.c (execute) [ENABLE_VALGRIND_CHECKING]: Arrange to prepend
	VALGRIND_PATH -q to each command.

From-SVN: r59309