bitcomp: Remove the t4 decoding from libosmocore

As outlined by mail on the 13th of July the tree based approach to
decoding in the PCU is faster by order of magnitude. Instead of having a
slow implementation in the library and a quick one in the PCU, let's
only have a quick one in the PCU and at some point in the future move it
to libosmocore.

Execute the plan and remove t4_decode.

Change-Id: I021424444625a097560d086c217c81eac4a5ee44
4 files changed