libtorrent-rasterbar fails with "Could not link against boost_thread-boost_thread"

[Christian Sørmarken]

Dear community,

While attempting to build libtorrent-rasterbar 
net-p2p/libtorrent-rasterbar-15, it fails make config. The last output 
is as following:

Checking for boost libraries:
checking for boostlib >= 1.36... yes
checking whether the Boost::System library is available... yes
checking for exit in -lboost_system... yes
checking whether the Boost::Filesystem library is available... yes
checking for exit in -lboost_filesystem... yes
checking whether the Boost::Thread library is available... yes
checking for exit in -lboost_thread... no
checking for exit in -lboost_thread-boost_thread... no
configure: error: Could not link against boost_thread-boost_thread !
===>  Script "configure" failed unexpectedly.

I am currently running FreeBSD 9.0-RELEASE, and compiling with lang/gcc 
(version 4.6). I have the following in make.conf:

WITH_OPENSSL_PORT=YES
WITHOUT_X11=yes
CPUTYPE?=native
.if !empty(.CURDIR:M/usr/ports/*) && exists(/usr/local/bin/gcc46)
CC=gcc46
CXX=g++46
CPP=cpp46
.endif
# added by use.perl 2012-06-30 08:15:47
PERL_VERSION=5.12.4

and the following in /etc/libmap.conf

libgcc_s.so.1   gcc46/libgcc_s.so.1
libgomp.so.1    gcc46/libgomp.so.1
libobjc.so.3    gcc46/libobjc.so.3
libssp.so.0     gcc46/libssp.so.0
libstdc++.so.6  gcc46/libstdc++.so.6

Any idea why libtorrent-rasterbar is unable to link against 
boost_thread-boost_thread? Python27 is compiled WITH "THREADS Threading 
support" and WITHOUT "PTH       Use GNU Pth for 
threading/multiprocessing". Am I simply overlooking something here?

Best regards,
Chris