patcht7500: remove non-existant C_LOCALE_OUTPUT prereq

> The C_LOCALE_OUTPUT prerequisite was removed in b1e079807b (tests:
> remove last uses of C_LOCALE_OUTPUT, 2021-02-11), where Ævar noted:
>
>     I'm not leaving the prerequisite itself in place for in-flight changes
>     as there currently are none that introduce new tests that rely on it,
>     and because C_LOCALE_OUTPUT is currently a noop on the master branch
>     we likely won't have any new submissions that use it.
>
> One more use of C_LOCALE_OUTPUT did creep in with 3d1bda6b5b (t7500: add
> tests for --fixup=[amend|reword] options, 2021-03-15).  This causes a
> number of the tests to be skipped by default:
>
>     ok 35 # SKIP --fixup=reword: incompatible with --all (missing C_LOCALE_OUTPUT)
>     ok 36 # SKIP --fixup=reword: incompatible with --include (missing C_LOCALE_OUTPUT)
>     ok 37 # SKIP --fixup=reword: incompatible with --only (missing C_LOCALE_OUTPUT)
>     ok 38 # SKIP --fixup=reword: incompatible with --interactive (missing C_LOCALE_OUTPUT)
>     ok 39 # SKIP --fixup=reword: incompatible with --patch (missing C_LOCALE_OUTPUT)
>
> Remove the C_LOCALE_OUTPUT prerequisite from these tests so they are
> not skipped.
>
> Signed-off-by: Todd Zullinger <tmz@pobox.com>
> ---
> I noticed this while testing 2.32.0-rc0.  I grep for skipped tests to help me
> catch missing requirements in the Fedora packages.
>
>  t/t7500-commit-template-squash-signoff.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
> index 9092db5fdc..7d02f79c0d 100755
> --- a/t/t7500-commit-template-squash-signoff.sh
> +++ b/t/t7500-commit-template-squash-signoff.sh
> @@ -413,7 +413,7 @@ test_expect_success 'amend! commit allows empty commit msg body with --allow-emp
>  '
>  
>  test_fixup_reword_opt () {
> -	test_expect_success C_LOCALE_OUTPUT "--fixup=reword: incompatible with $1" "
> +	test_expect_success "--fixup=reword: incompatible with $1" "
>  		echo 'fatal: reword option of --fixup is mutually exclusive with'\
>  			'--patch/--interactive/--all/--include/--only' >expect &&
>  		test_must_fail git commit --fixup=reword:HEAD~ $1 2>actual &&

> Thanks. This is obviously correct.
>
> Junio (added to CC): I also think it makes sense to pull this into rc1,
> since we have 3d1bda6b5b new in 2.32.0, and will be skipping this part
> of its tests everywhere without this patc.h