[lldb/CMake] Rename LLDB_DISABLE_PYTHON to LLDB_ENABLE_PYTHON

This matches the naming scheme used by LLVM and all the other optional
dependencies in LLDB.

Differential revision: https://reviews.llvm.org/D71482

lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp

@@ -8,7 +8,7 @@
 
 #include "lldb/Host/Config.h"
 
-#ifndef LLDB_DISABLE_PYTHON
+#if LLDB_ENABLE_PYTHON
 
 // LLDB Python header must be included first
 #include "lldb-python.h"
@@ -3293,4 +3293,4 @@ void ScriptInterpreterPythonImpl::AddToSysPath(AddLocation location,
 //
 // void ScriptInterpreterPythonImpl::Terminate() { Py_Finalize (); }
 
-#endif // LLDB_DISABLE_PYTHON
+#endif