contrib/gdb-add-index.sh -dwarf-5
    
    ------------------------------------------------------------------------------
    (gdb) help save gdb-index
    Save a gdb-index file.
    Usage: save gdb-index [-dwarf-5] DIRECTORY
    
    No options create one file with .gdb-index extension for pre-DWARF-5
    compatible .gdb_index section.  With -dwarf-5 creates two files with
    extension .debug_names and .debug_str for DWARF-5 .debug_names section.
    ------------------------------------------------------------------------------
    
    But gdb-add-index command provided no way how to pass the -dwarf-5 option.
    
    gdb/ChangeLog
    2018-07-07  Jan Kratochvil  <jan.kratochvil@redhat.com>
    
    	* contrib/gdb-add-index.sh ($dwarf5): New, use it.