Makefile: enable SNPRINTF_RETURNS_BOGUS for HP-UX

In 81cc66a, customization has been added to Makefile for supporting
HP-UX, but git commit is still problematic. This should fix the issue.

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Acked-by: Robert Schiele <rschiele@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -727,6 +727,7 @@ ifeq ($(uname_S),HP-UX)
 	NO_UNSETENV = YesPlease
 	NO_HSTRERROR = YesPlease
 	NO_SYS_SELECT_H = YesPlease
+	SNPRINTF_RETURNS_BOGUS = YesPlease
 endif
 ifneq (,$(findstring MINGW,$(uname_S)))
 	NO_MMAP = YesPlease