Feature/nimble user args

[redradist]

This MR fixes some issues when using code in C++ and also added extra user-defined argument for using for example in C++ wrapper

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[prasad-alatkar]

Hi @redradist , most of the changes look specific to upstream NimBLE. It would be really great if you raise PR on mynewt NimBLE first here: https://github.com/apache/mynewt-nimble/pulls

[redradist]

Hi @redradist , most of the changes look specific to upstream NimBLE. It would be really great if you raise PR on mynewt NimBLE first here: https://github.com/apache/mynewt-nimble/pulls

@prasad-alatkar I've tired first it already apache#697
... But they decided that it is not needed and not useful at that moment and it is a hack (but it is not !!)