Introduced support for external python tests

The test scripts warn about missing documentation, untested configs,
check common errors, and stub out testing individual VTY commands.
The scripts have been moved to the another osmocom repository,
python/osmo-python-tests

The features were requested by zecke.
diff --git a/openbsc/configure.ac b/openbsc/configure.ac
index cdefcaf..3dd2212 100644
--- a/openbsc/configure.ac
+++ b/openbsc/configure.ac
@@ -114,6 +114,21 @@
 
 CHECK_TM_INCLUDES_TM_GMTOFF
 
+AC_ARG_ENABLE([vty_tests],
+		AC_HELP_STRING([--enable-vty-tests],
+				[Include the VTY tests in make check [default=no]]),
+		[enable_vty_tests="$enableval"],[enable_vty_tests="no"])
+if test "x$enable_vty_tests" = "xyes" ; then
+	AM_PATH_PYTHON
+	AC_CHECK_PROG(OSMOTESTVTY_CHECK,osmotestvty.py,yes)
+	 if test "x$OSMOTESTVTY_CHECK" != "xyes" ; then
+		AC_MSG_ERROR([Please install osmocom-python to run the vty tests.])
+	fi
+fi
+AC_MSG_CHECKING([whether to enable VTY tests])
+AC_MSG_RESULT([$enable_vty_tests])
+AM_CONDITIONAL(ENABLE_VTY_TESTS, test "x$enable_vty_tests" = "xyes")
+
 dnl Generate the output
 AM_CONFIG_HEADER(bscconfig.h)