Big upstream commit:

  Major changes:
    - Add support for single-threaded decompression to reduce memory usage
    - Add vector support

  Minor changes:
    - Bump STF library version to 1.4
    - Make STFReaderWriterBase move assignable/constructable
    - Allow comment records anywhere in the trace
    - Allow process ID records in the header
    - Add STFInst::write method that filters out specified record types
    - Fix typo in error message
    - Add std::initializer_list constructor for InstRegRecord
    - Fix print_utils to match new disassembler interface
    - Remove print_utils::printOpcodeWithDisassembly since it isn't used outside of stf_dump
    - Add generator definitions for Athena and stf_morph
    - Remove STF_TOOL_VERSION
    - Add convenience methods for getting latest TraceInfoRecord from a reader and checking
      whether a TraceInfoRecord was created by a specific generator
    - Split STF_GEN enum into its own file(s)
    - Clean up Doxygen comments

  Bug fixes:
    - Clear STFRecordMap in copy assignment operator to fix memory leak in stf_check
    - Fix bug in constexpr log2 function
    - Fix record reuse bug caused by not always resizing data vector in InstRegRecord
    - STFCompressedIFstream: Fix race condition in destructor that caused a segfault if the
      second reader thread was still running at destruction time