- Fix #222: --with-rpath, fails to rpath python lib.

acx_python.m4

@@ -58,6 +58,11 @@ $ac_distutils_result])
         AC_MSG_RESULT([$PYTHON_LDFLAGS])
         AC_SUBST([PYTHON_LDFLAGS])
 
+        if test -z "$PYTHON_LIBDIR"; then
+                PYTHON_LIBDIR=`$PYTHON -c "from distutils.sysconfig import *; \
+                        print(get_config_var('LIBDIR'));"`
+        fi
+
         #
         # Check for site packages
         #