Compile error with tcl-threads

[Jack L.]

I keep getting these types of compiler errors when tcl-threads-8.4.11,1 is
installed instead of regular tcl. What is the difference between a threaded
tcl and regular tcl and is there any way to compile epic5 with threaded tcl?

cc -O2 -fno-strict-aliasing -pipe -march=prescott -I
/usr/local/include/tcl8.4 -I./../include -I../include -c info.c
cc -O2 -fno-strict-aliasing -pipe -march=prescott -I
/usr/local/include/tcl8.4 -rpath=/usr/local/lib -o epic5 alias.o alist.o
array.o clock.o commands.o compat.o crypt.o ctcp.o  dcc.o debug.o exec.o
files.o flood.o functions.o gailib.o glob.o  hook.o if.o ignore.o input.o
irc.o ircaux.o  ircsig.o keys.o lastlog.o list.o log.o logfiles.o mail.o
names.o network.o  newio.o notify.o numbers.o output.o parse.o queue.o reg.o
screen.o server.o ssl.o status.o term.o timer.o translat.o vars.o who.o
window.o words.o  tcl.o info.o -L/usr/local/lib -ltcl84 -lncurses  -lssl
-lcrypto -lcrypt -lm
/usr/local/lib/libtcl84.so: undefined reference to `pthread_attr_destroy'
/usr/local/lib/libtcl84.so: undefined reference to `pthread_create'
/usr/local/lib/libtcl84.so: undefined reference to `pthread_attr_init'
/usr/local/lib/libtcl84.so: undefined reference to `pthread_exit'
/usr/local/lib/libtcl84.so: undefined reference to `pthread_attr_setscope'
/usr/local/lib/libtcl84.so: undefined reference to
`pthread_attr_setstacksize'
/usr/local/lib/libtcl84.so: undefined reference to
`pthread_attr_setdetachstate'
/usr/local/lib/libtcl84.so: undefined reference to `pthread_join'
/usr/local/lib/libtcl84.so: undefined reference to `pthread_cond_timedwait'
*** Error code 1

Stop in /usr/ports/irc/epic5/work/epic5-0.0.5/source.
*** Error code 1

Stop in /usr/ports/irc/epic5/work/epic5-0.0.5.
*** Error code 1

Stop in /usr/ports/irc/epic5.
musirc#