Fix strlen being used on uninitialized data

src/metaflac/utils.c

@@ -76,6 +76,11 @@ void local_strcat(char **dest, const char *source)
 	*dest = safe_realloc_add_3op_(*dest, ndest, /*+*/nsource, /*+*/1);
 	if(*dest == NULL)
 		die("out of memory growing string");
+	/* If ndest == 0, strlen in safe_strncat reads
+	 * uninitialized data. To prevent that, set first character
+	 * to zero */
+	if(ndest == 0)
+		*dest[0] = 0;
 	safe_strncat(*dest, source, outlen);
 }