Patch to support PowerPC 4xx dlmzb instruction

[David Edelsohn]

2006-03-12  Joseph S. Myers  <joseph@codesourcery.com>

	    * config/rs6000/rs6000.opt (mdlmzb): New option.
	    (mupdate, mno-update): Use Var not Mask.
	    * doc/invoke.texi (-mdlmzb): Document.
	    * config/rs6000/rs6000.c (rs6000_override_options): Enable
	    -mdlmzb
	    for 405 and 440.
	    * config/rs6000/rs6000.md: Add dlmzb support for 405 and 440.

2006-03-12  Joseph S. Myers  <joseph@codesourcery.com>

	    * gcc.target/powerpc/405-dlmzb-strlen-1.c,
	    gcc.target/powerpc/440-dlmzb-strlen-1.c: New tests.

The patch is okay, but I agree with Andrew that -mupdate is not the best
bit to move.  Could you modify the patch to use one of the other bits that
Andrew suggested?

Thanks, David