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

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

--- Comment #15 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-16 branch has been updated by Jonathan Wakely
<[email protected]>:

https://gcc.gnu.org/g:7f84e9af923261f3fdd7f15b064c449b7d4157b9

commit r16-9547-g7f84e9af923261f3fdd7f15b064c449b7d4157b9
Author: Jonathan Wakely <[email protected]>
Date:   Wed Jul 29 16:55:39 2026 +0100

    libstdc++: Fix grep for linker warning about --gc-sections [PR126452]

    Current versions of GNU ld print "warning" with a lowercase 'w' so
    adjust the grep patter. Also use LC_ALL=C to ensure the warning isn't
    translated.

    Because m4 uses square brackets as quotes, we need to use double
    brackets in the grep pattern to expand to "[Ww]" in the configure
    script.

    libstdc++-v3/ChangeLog:

            PR libstdc++/126452
            * acinclude.m4 (GLIBCXX_CHECK_LINKER_FEATURES): Use LC_ALL_C and
            match both "Warning" and "warning" in ld output.
            * configure: Regenerate.

    Reviewed-by: Jakub Jelinek <[email protected]>
    (cherry picked from commit b7ce998a967639b955159eeeae940cb069c518d8)