Added linking to libpthread for MPI compilation also

Author: giltirn

configure.ac

@@ -46,6 +46,7 @@ AS_IF(
     AC_MSG_NOTICE([MPI use is enabled, checking compilation with MPI is possible])
     AC_CHECK_HEADER(mpi.h, [], [AC_MSG_FAILURE([["Cannot find MPI header"]])] )
     AC_DEFINE([USE_MPI],[1],[Use MPI])
+    LIBS+="-lpthread"
 ],
 [test "x$enable_mpi" == "xno"], [
     AC_MSG_NOTICE([MPI use is disabled])