fix PYHTON_BIN typo

fix --with-rlm-python-lib-dir to actually use that dir

--- src/modules/rlm_python/configure.ac.orig	2018-04-17 17:12:27.000000000 +0000
+++ src/modules/rlm_python/configure.ac
@@ -9,7 +9,7 @@
 	AC_PROG_CPP
 
 	dnl extra argument: --with-rlm-python-bin
-	PYHTON_BIN=
+	PYTHON_BIN=
 	AC_ARG_WITH(rlm-python-bin,
 	[  --with-rlm-python-bin=PATH   Path to python binary []],
 	[ case "$withval" in
@@ -74,8 +74,12 @@
 		PY_SYS_VERSION=`${PYTHON_BIN} -c 'import sys ; print(sys.version[[0:3]])'`
 		AC_MSG_NOTICE([Python sys.version \"${PY_SYS_VERSION}\"])
 
-		PY_LIB_DIR="$PY_EXEC_PREFIX/lib/python${PY_SYS_VERSION}/config"
-		PY_LIB_LOC="-L$PY_EXEC_PREFIX/lib/python${PY_SYS_VERSION}/config"
+		if [ -z "$PY_LIB_DIR" ]; then
+			PY_LIB_DIR="$PY_EXEC_PREFIX/lib/python${PY_SYS_VERSION}/config"
+			PY_LIB_LOC="-L$PY_EXEC_PREFIX/lib/python${PY_SYS_VERSION}/config"
+		else
+			PY_LIB_LOC="-L$PY_LIB_DIR"
+		fi
 
 		PY_MAKEFILE="$PY_EXEC_PREFIX/lib/python${PY_SYS_VERSION}/config/Makefile"
 		if test -f ${PY_MAKEFILE}; then