2021-01-28  David Anderson
    * createirepformfrombinary.cc: Now adds DW_FORM_CLASS_EXPERLOC
      as a uniform way to handle dwarf expressions across
      all DWARF2 and later versions. libdwarf changed a little
      to support this as the old way just did not work.
    * dwarfdump.cc: Added option --add-skip-branch-ops to create
      special DW_OP_skip and DW_OP_bra entries to verify
      dwarfdump error checking works properly.
    * general.h: Added bool addskipbranch for the
      --add-skip-branch-ops option.
    * irepattrtodbg.c: Corrected EXPRLOC handling
      to actually emit expressions.
    * irepdie.h: Reformatted the copyright to fit
      properly within libdwarf line lengths.
    * irepform.h: Reformatted copyright.
      Added new methods so block and EXPRLOC
      can emit proper expr byte blobs.
    * ireptodbg.cc: When --add-skip-branch-ops present
      this emits some special crafted expressions that
      emit DW_OP_bra and skip with errors so dwarfdump
      can report on them.