*.c static functions: add missing __attribute__((format))

Add missing __attribute__((format)) function attributes to various
"static" functions that take printf arguments.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

add-patch.c

@@ -280,6 +280,7 @@ static void add_p_state_clear(struct add_p_state *s)
 	clear_add_i_state(&s->s);
 }
 
+__attribute__((format (printf, 2, 3)))
 static void err(struct add_p_state *s, const char *fmt, ...)
 {
 	va_list args;