bfd doc chew

bfd doc chew

I got tired of watching chew.c being compiled a dozen or more times
each time I do a binutils build.

	* Makefile.am (MKDOC): Use $@ in command.
	(aoutx.texi): New rule, depend on aoutx.stamp.  Move old rule..
	(aoutx.stamp): .. to here.  Don't depend on chew.c, depend on MKDOC
	and omit recursive MAKE.  Use $< in command.
	(archive.texi, archures.texi, bfdt.texi, cache.texi, coffcode.texi,
	core.texi, elf.texi, elfcode.texi, mmo.texi, format.texi, libbfd.texi,
	bfdio.texi, bfdwin.texi, opncls.texi, reloc.texi, section.texi,
	syms.texi, targets.texi, init.texi, hash.texi, linker.texi): Similarly.
	(DISTCLEANFILES): Remove *.stamp.
	* Makefile.in: Regenerate.