Use skiplist-based FastCallSet within trace::CallSet

Use skiplist-based FastCallSet within trace::CallSet

The FastCallSet supports only ranges step of 1 and freq of
FREQUENCY_ALL, so store any such ranges there, and store all other
ranges in the existing, linear list of CallRange.

For manually entered call sets on the command line, the performance
hit of the linear lookup was not generally a problem. But when taking
the (potentially huge) output of "apitrace trim --print-callset" the
performance hit made things quite painful. This makes things usable
again.