Regressions on 8 at revision 268717 vs revision 268468

[H.J. Lu]

New failures:
FAIL: g++.dg/cpp1z/constexpr-lambda8.C   (test for excess errors)
FAIL: g++.dg/cpp1z/constexpr-lambda8.C   (test for excess errors)

New passes:
FAIL: gcc.target/i386/mpx/memmove-1.c   -O0  execution test
FAIL: gcc.target/i386/mpx/memmove-1.c   -O1  execution test
FAIL: gcc.target/i386/mpx/memmove-1.c   -O2  execution test
FAIL: gcc.target/i386/mpx/memmove-1.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  execution test
FAIL: gcc.target/i386/mpx/memmove-1.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  execution test
FAIL: gcc.target/i386/mpx/memmove-1.c   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
FAIL: gcc.target/i386/mpx/memmove-1.c   -O3 -g  execution test
FAIL: gcc.target/i386/mpx/memmove-1.c   -Os  execution test