[Bug libstdc++/126452] Typo in check for --gc-sections support in acinclude.m4

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126452

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Does GNU ld even print a warning of that form?

If I give a bad option I get:

ld: unrecognized option '--gd-section'


maybe we should just grep for "--gc-sections" and if that appears in the
output, assume ld doesn't know the option.

I don't think we can look for no output, because the $LD command emits a
warning for me:

ld: warning: cannot find entry symbol _start; not setting start address