Fix typo in variable name

Fix spelling $cppfags2 => $cppflags2 in file Configurations/windows-makefile.tmpl

CLA: trivial

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from #22771)

(cherry picked from commit 6d552a5)

Configurations/windows-makefile.tmpl

@@ -294,7 +294,7 @@ RCOUTFLAG={- $target{rcoutflag} -}$(OSSL_EMPTY)
 
 CNF_ASFLAGS={- join(' ', $target{asflags} || (),
                          @{$config{asflags}}) -}
-CNF_CPPFLAGS={- our $cppfags2 =
+CNF_CPPFLAGS={- our $cppflags2 =
                     join(' ', $target{cppflags} || (),
                               (map { '-D'.quotify1($_) } @{$target{defines}},
                                                          @{$config{defines}}),