powerpc ld configure

powerpc ld configure

This fixes a few problems in the powerpc ld configury.
1) Using powerpc*le-* to test for powerpcle and powerpc64le would
   incorrectly match a target triple like powerpc-apple-elf.
2) In the same vein, *64* could match 64 in the user supplied MANUF-OS
   part of the target triple.
3) tooldir vars were missing, and some target aliases would result in
   ridiculous values for those tdir_* vars given.
4) Since 2016-04-25, BE support was added automatically when asking
   for an LE target.  If that is a good idea, then so is adding LE
   support when asking for BE.

	* configure.tgt (powerpc*-*-linux* et al): Rewrite, adding LE
	support for BE.  First output all target endian configury
	values, then opposite endian.  Handle more tooldirs.  Fix
	bogus matches with strings in MANUF-OS part of target triple.