patched that caused regression PR opt/8634

[Janis Johnson]

The regression reported in PR optimization/8634 showed up
starting with this patch (strange but true):

Fri Dec 21 23:30:14 CET 2001  Jan Hubicka  <jh@suse.cz>

	* i386.h (TARGET_CPU_DEFAULT_pentium_mmx): New.
	(TARGET_CPU_DEFAULT_*): Renumber.

I used this test case that Wolfgang provided.  It aborts
when the wrong code is generated for -O2 on i686-linux:

--------------
/* incorrect code for inlining of memcpy under -O2 */

#include <string.h>
#include <stdlib.h>

int
main ()
{
  int i;
  char buffer[8];
  const char head[8] =
    { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H' };
  memcpy (buffer, head, 8);
  for (i = 0; i < 8; i++)
    if (head[i] != buffer[i])
      abort ();
  return 0;
}
--------------

I've added this information to the PR.

Janis