[testsuite] tolerate enabled but missing language frontends

[Jeff Law]

On 6/28/23 05:25, Alexandre Oliva via Gcc-patches wrote:
> 
> When a language is enabled but we run the testsuite against a tree in
> which the frontend compiler is not present, help.exp fails.  It
> recognizes the output pattern for a disabled language, but not a
> missing frontend.  Extend the pattern so that it covers both cases.
> 
> Tested on x86_64-linux-gnu.  Ok to install?
> 
> 
> for  gcc/testsuite/ChangeLog
> 
> 	* lib/options.exp (check_for_options_with_filter): Handle
> 	missing frontend compiler like disabled language.
ok
Jeff