The middle end support for strlcpy consists of transforming calls to __strlcpy_chk to the function itself if the buffer overflow checking overhead can be avoided. This change extends the support to also optimize a subset of calls to the function itself, similar to snprintf.
The strlcpy and strlcat functions have both recently been added to the next revision of POSIX (see issue 986). If/when this proposed enhancement is accepted I'll look into adding minimal support for strlcat as well.