[PATCH] Simplify strncat.

[Paul Eggert]

Thanks, this is much better than worrying about how to pacify GCC. The 
code could be made a bit shorter and clearer with mempcpy, and there's 
no longer any need to distinguish between s and s1, so I suggest the 
following minor rewrite, which shrinks the code size by another 26 bytes 
(16%) on my x86-64 platform.

char *
STRNCAT (char *s1, const char *s2, size_t n)
{
   char *s1_end = mempcpy (s1 + strlen (s1), s2, __strnlen (s2, n));
   *s1_end = '\0';
   return s1;
}