The strsep() function is not defined by POSIX. Additionally
auto-tools has been having some obscure issues detecting
or linking the provided implementation into libcompat on
Windows and Solaris respectively. Which are the two known
OS requiring it.
Investigation of its use in Squid revealed that it can be
replaced with strcspan() which is both portable and more
efficient since it also removes the need for several
strdup()/free() operations used to protect Squid from
strsep() memory fiddling.