nrf_strerror.h without extern "C" linkage specification

[Anatol Ivanov]

Hi,

Please add extern "C" to nrf_strerror.h header in next coming SDK release to make it more usable with c++.

Regards, Anatol

[Radoslaw Koppel]

Thanks for the feedback. Task in our internal bug tracker created.

[Radoslaw Koppel]

Prepared in master branch for the nearest release.