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

[sjames at gcc dot gnu.org via Gcc-bugs]

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

--- Comment #1 from Sam James <sjames at gcc dot gnu.org> ---
I feel like it should probably be testing for no output anyway.

In any case, if going to keep it as it is, please add LC_ALL=C before $LD too.