#228 PTrace::Begin() longer full thread name

[Fabrizio Ammollo]

- src/ptlib/common/osutils.cxx: PTrace::Begin() prints entirely thread
names long at most 12 chars and only partially (first 10, "...", last
10) those longer than 12 chars, in our opinion the first print should be
changed to the full 23 chars

[Fabrizio Ammollo]

The patch