mingw: fix a typo in the msysGit-specific section

The msysGit project (i.e. Git for Windows 1.x' SDK) is safely dead for
*years* already. This is probably the reason why nobody caught this typo
until Carlo Arenas spotted a copy-edited version of it nearby.

It is probably about time to rip out the remainders of msysGit/MSys1
support, but that can safely wait a bit longer, and we can at least fix
the typo for now.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.mak.uname

@@ -571,7 +571,7 @@ ifneq (,$(wildcard ../THIS_IS_MSYSGIT))
 	INTERNAL_QSORT = YesPlease
 	HAVE_LIBCHARSET_H = YesPlease
 	NO_GETTEXT = YesPlease
-	COMPAT_CLFAGS += -D__USE_MINGW_ACCESS
+	COMPAT_CFLAGS += -D__USE_MINGW_ACCESS
 else
 	ifneq ($(shell expr "$(uname_R)" : '1\.'),2)
 		# MSys2