t7500: remove non-existant C_LOCALE_OUTPUT prereq

t7500: 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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>