Regressions on trunk at revision 171051 vs revision 171048

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

New failures:

New passes:
FAIL: gcc.dg/guality/vla-1.c  -O1  line 17 sizeof (a) == 6
FAIL: gcc.dg/guality/vla-1.c  -O2  line 17 sizeof (a) == 6
FAIL: gcc.dg/guality/vla-1.c  -O3 -fomit-frame-pointer  line 17 sizeof (a) == 6
FAIL: gcc.dg/guality/vla-1.c  -O3 -g  line 17 sizeof (a) == 6
FAIL: gcc.dg/guality/vla-1.c  -Os  line 17 sizeof (a) == 6