SF: _running() in bpsource does not remember set value

[iondev33]

Hey I didn't notice that there is a ticket option on sourceforge and just create a merge request right away (https://sourceforge.net/p/ion-dtn/code/merge-requests/3/).

Anyway, as stated in the merge request:
The implementation of running() in bpsource has a bug that might prevent the application from closing. As I understand, the behaviour of running() should be that it remembers the last value passed to it and returns this value whenever called with NULL. To achieve that, variable has to be declared as static to keep the value between function calls.