Regressions on trunk at revision 178686 vs revision 178665

[H.J. Lu Intel64 Core 2/i7]

New failures:
FAIL: gcc.dg/guality/vla-1.c  -Os  line 17 sizeof (a) == 6

New passes:
FAIL: gcc.dg/guality/vla-1.c  -O1  line 17 i == 5
FAIL: gcc.dg/guality/vla-1.c  -O1  line 17 sizeof (a) == 6
FAIL: gcc.dg/guality/vla-1.c  -O2 -flto  line 17 i == 5
FAIL: gcc.dg/guality/vla-1.c  -O2 -flto -flto-partition=none  line 17 i == 5