Regressions on master at commit r12-7861 vs commit r12-7847 on Linux/x86_64

[H.J. Lu]

New failures:

New passes:
FAIL: g++.dg/cpp0x/variadic-alias3.C  -std=c++17 (internal compiler error: in hashtab_chk_error, at hash-table.cc:137)
FAIL: g++.dg/cpp0x/variadic-alias3.C  -std=c++17 (test for excess errors)