Make IntervalMapVector's count() method const.
Print debugging information to errs if MappedStmt::fromMetadata() fails.
Add call detection and recording for the following (linux) functions:
  __ctype_b_loc()
  __ctype_tolower_loc()
  __ctype_toupper_loc()

Add isKnownMemoryRegionAt() to TraceThreadListener, to check if there is an
existing known memory region already covering a given address.