Makefile: use ' ', not non-existing $(wspfx_SQ)
Change the use of a non-existing variable added in my
0b6d0bc9246 (Makefiles: add and use wildcard "mkdir -p" template,
2022-03-03) to use the hardcoded whitespace padding for "QUIET" rules
instead. The wspfx_SQ was left from an earlier (rebased out) commit
preceding
0b6d0bc9246[1].
1. https://lore.kernel.org/git/patch-v4-8.9-
3733b0c8df1-20220302T124320Z-avarab@gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>