optimization/10087: [3.3/3.4 regression] optimizer produces wrong code when indexing 2D array

[Glen Nakamura]

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10087

Additional analysis of the problem and patch located at:
http://gcc.gnu.org/ml/gcc-patches/2003-03/msg01932.html

The proposed fix is somewhat hackish, but it should fix the problem.
BTW, I didn't update the comments about the use of 'same' in struct induction
for bivs in loop.h

- glen