bitrev_test: don't omit last byte from test result check

The osmo_hexdump of the output in sh_chk() omitted the last byte of the
returned bytes from the osmo_nibble_shift_*() functions.

Determine the number of bytes from nibbles divided by two plus one for any odd
nibble number. Output this number of bytes of output data.

Memset the output buffer to get well-defined bytes for unwritten places.

Also assert that we have enough buffer length for all nibbles.

Change-Id: I011f42bca555caec0dfe8688ff1f28303fa04fad
2 files changed