* Append \p b to \p a.
*
* \return If \a a is \p NULL, return a pointer to a copy of \a b, i.e.
- * para_strcat(NULL, b) is equivalent to para_strdup(b). If \a b is \p NULL,
+ * adu_strcat(NULL, b) is equivalent to adu_strdup(b). If \a b is \p NULL,
* return \a a without making a copy of \a a. Otherwise, construct the
* concatenation \a c, free \a a (but not \a b) and return \a c.
*