Regressions on trunk at revision 275404 vs revision 275387

[H.J. Lu]

New failures:
FAIL: 23_containers/span/get_neg.cc (test for excess errors)
FAIL: g++.dg/ubsan/pr59415.C   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
FAIL: g++.dg/ubsan/pr59415.C   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (test for excess errors)

New passes:
FAIL: gcc.dg/plugin/location-overflow-test-pr83173.c -fplugin=./location_overflow_plugin.so  scan-file-not # (?!1 [^\r\n]+location-overflow-test-pr83173-1.h" 1)[0-9]+ [^\r\n]+location-overflow-test-pr83173-1.h"