Regressions on trunk at revision 169516 vs revision 169512

[H.J. Lu Intel64-profiled]

New failures:
FAIL: gcc.dg/guality/vla-2.c  -Os  line 25 sizeof (a) == 6 * sizeof (int)

New passes:
FAIL: gcc.dg/guality/vla-2.c  -O1  line 25 sizeof (a) == 6 * sizeof (int)
FAIL: gcc.dg/guality/vla-2.c  -O2 -flto  line 25 sizeof (a) == 6 * sizeof (int)