Do not trust MSys2's MinGW gettext.sh

It does not quite work because it produces DOS line endings which the
shell does not like at all.

This lets t3406, t3903, t4254, t7400, t7401, t7406 and t7407 pass.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

config.mak.uname

@@ -559,6 +559,7 @@ else
 		INTERNAL_QSORT = YesPlease
 		HAVE_LIBCHARSET_H = YesPlease
 		NO_GETTEXT =
+		USE_GETTEXT_SCHEME = fallthrough
 		USE_LIBPCRE= YesPlease
 		NO_CURL =
 		USE_NED_ALLOCATOR = YesPlease