BOOST_THREAD_LDPATH empty

[Alessandro-Barbieri]

an empty BOOST_THREAD_LDPATH is causing this issue

/bin/sh ../../libtool  --tag=CXX   --mode=link x86_64-pc-linux-gnu-g++  -Os -pipe -march=native -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -L -R -L/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0 -R/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0 -DCLUSTERING_SUITE -I/var/tmp/portage/sys-cluster/clusteringsuite-2.6.9-r3/work/clustering-suite-2.6.9/include -I/var/tmp/portage/sys-cluster/clusteringsuite-2.6.9-r3/work/clustering-suite-2.6.9/src/BasicClasses -I/var/tmp/portage/sys-cluster/clusteringsuite-2.6.9-r3/work/clustering-suite-2.6.9/common_utilities -I/usr/include/libxml2 -I/usr/include -I/usr/include -I/usr/include -I/usr/include -I/usr/include -DNDEBUG -I/usr/include -Wl,-O1 -Wl,--as-needed -o libBasicClasses.la -rpath /usr/lib64 libBasicClasses_la-Error.lo libBasicClasses_la-FileNameManipulator.lo libBasicClasses_la-SystemMessages.lo libBasicClasses_la-Utilities.lo libBasicClasses_la-Timer.lo -lxml2 -lmpi_cxx -lboost_thread-mt -lboost_system-mt -pthread  -lmpfr -lgmp -lCGAL -lCGAL_Core 
libtool:   error: require no space between '-L' and '-R'