This error happens when a program is linked to two different threads libraries. Both use init sections to set themselves up, so when the second one gets initialized it complains with that very obscure error message.
(...)
Try running the following script:

#! /bin/sh
( find -s /usr/local/lib /usr/X11R6/lib -name "lib*.so"
 find -s /usr/local/bin /usr/X11R6/bin/
) |
xargs ldd -a 2>/dev/null |
awk '
 /^[^\t]/ { cmd=$1 }
 /^\tlibc_r.so/ { printf "%s\t%s\n",cmd,$3 }
'

That should print out all the libraries and programs that are explicitly linked to libc_r.so. Rebuild the ports they came from and you should be okay.