Merge: nitc can inline redefinitions with -D

nitc with --global and --semi-global tries to inline things, but methods with an explicit `constant_value` (i.e. defined with `-D`) were not recognized when asked: ``can I inline this?''

The inlining itself does not require specific code.

Close #1793

Pull-Request: #1794
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>