OsmocomTETRA

Running tetra-rx on a capture with lots of bit errors is not deterministic. Investigation with Valgrind shows various errors about uninitialised values in libosmocore's viterbi decoder.

The cause appears to lie in lower_mac/viterbi.c. The only function there allocates space for 864 symbols and then fills it with the symbols received. However, sym_count is sometimes less than 864, leaving the rest of the array uninitialized.

Initializing it with int8_t vit_inp[864*4] = {0}; fixes the problem.