Don't crash when we build with python enabled, yet we don't link in the lldb::SB* API layer.

Previously the lldb-platform and lldb-gdbserver would crash.

llvm-svn: 201872

lldb/source/Interpreter/ScriptInterpreterPython.cpp

@@ -2542,8 +2542,8 @@ ScriptInterpreterPython::InitializePrivate ()
     Py_InitializeEx (0);
 
     // Initialize SWIG after setting up python
-    assert (g_swig_init_callback != NULL);
-    g_swig_init_callback ();
+    if (g_swig_init_callback)
+        g_swig_init_callback ();
 
     // Update the path python uses to search for modules to include the current directory.