[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/lldb-python.h

@@ -14,9 +14,7 @@
 // Python.h needs to be included before any system headers in order to avoid
 // redefinition of macros
 
-#ifdef LLDB_DISABLE_PYTHON
-// Python is disabled in this build
-#else
+#if LLDB_ENABLE_PYTHON
 #include "llvm/Support/Compiler.h"
 #if defined(_WIN32)
 // If anyone #includes Host/PosixApi.h later, it will try to typedef pid_t.  We
@@ -42,6 +40,6 @@
 
 // Include python for non windows machines
 #include <Python.h>
-#endif // LLDB_DISABLE_PYTHON
+#endif
 
 #endif // LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_LLDB_PYTHON_H