strcatl() - concatenates strings
char *strcatl(outbuf,s1...sn,NULL)
char *outbuf,*s1...*sn;
strcatl() concatenates the "to" strings (s1...sn) into outbuf. The end
of the list is signalled by NULL.
Returns a pointer to the end of the concatenated output, in outbuf.
No check for buffer overflow is made.
A strcatl() of the form: strcatl(foo,bar,foo,NULL) does not work
correctly, although a strcatl() of the form
"strcatl(foo,foo,bar,NULL)" will. The destination string can only
be a source string if it is the first string in the list.