Fixed `format-nonliteral` warning

skeletons/REAL.c

@@ -131,7 +131,6 @@ REAL__dump(double d, int canonical, asn_app_consume_bytes_f *cb, void *app_key)
 	char local_buf[64];
 	char *buf = local_buf;
 	ssize_t buflen = sizeof(local_buf);
-	const char *fmt = canonical ? "%.17E" /* Precise */ : "%.15f" /* Pleasant*/;
 	ssize_t ret;
 
 	/*
@@ -166,7 +165,10 @@ REAL__dump(double d, int canonical, asn_app_consume_bytes_f *cb, void *app_key)
 	 * Use the libc's double printing, hopefully they got it right.
 	 */
 	do {
-		ret = snprintf(buf, buflen, fmt, d);
+        ret = snprintf(buf,
+                       buflen,
+                       canonical ? "%.17E" /* Precise */ : "%.15f" /* Pleasant*/,
+                       d);
 		if(ret < 0) {
 			/* There are some old broken APIs. */
 			buflen <<= 1;

skeletons/constr_TYPE.c

@@ -70,7 +70,7 @@ _print2fp(const void *buffer, size_t size, void *app_key) {
  * Some compilers do not support variable args macros.
  * This function is a replacement of ASN_DEBUG() macro.
  */
-void ASN_DEBUG_f(const char *fmt, ...);
+void CC_PRINTFLIKE(1, 2) ASN_DEBUG_f(const char *fmt, ...);
 void ASN_DEBUG_f(const char *fmt, ...) {
 	va_list ap;
 	va_start(ap, fmt);

skeletons/constraints.c

@@ -35,6 +35,7 @@ struct errbufDesc {
 };
 
 static void
+CC_PRINTFLIKE(4, 5)
 _asn_i_ctfailcb(void *key, const asn_TYPE_descriptor_t *td, const void *sptr,
                 const char *fmt, ...) {
     struct errbufDesc *arg = key;