Lihua Zhao authored 3 years ago and Brad King committed 3 years ago

Since commit b12aec6c (BinUtils: prefer bin utils matching the
compiler version extension, 2020-12-11, v3.20.0-rc1~171^2) we recognize
`clangg++` and `g++` but not `c++`.  Restore `[gc]` in place of `g`
in the regex, as we had before that change.

Fixes: #22069