fix: strcmp protection with NULL args

libbozo/src/string/strcmp.c

@@ -4,6 +4,8 @@ int strcmp(const char *s1, const char *s2)
 {
 	size_t i = 0;
 
+	if (!s1 || !s2)
+		return -1;
 	while (s1[i] == s2[i] && s1[i] != '\0')
 		i++;
 	return s1[i] - s2[i];