powerpc-lynxos and powerpc-windiss fixes

powerpc-lynxos and powerpc-windiss fixes

Enabling shared lib tests showed the powerpc-lynxos target is broken,
and has been for a long time.  The breakage happened in a 2005-05-07
patch of mine, git commit 3b36f7e62, I think.  There have been no bug
reports I recall so it seems the target is dead.  powerpc-windiss is
similarly broken.

This patch fixes the breakage, and puts the targets on the obsolete
list.

bfd/
	* config.bfd: Add powerpc-*-lynxos* and powerpc-*-windiss*
	to obsolete list.
ld/
	* emulparams/elf32ppcwindiss.sh: Rewrite to use elf32ppc.sh.
	* emulparams/ppclynx.sh: Likewise.