* dwarf2.h: Mention the location of the DWARF3 spec on the web.

* dwarf2.h: Mention the location of the DWARF3 spec on the web.
  (DW_AT_stride_size): Rename to DW_AT_bit_stride.
  (DW_AT_stride): Rename to DW_AT_byte_stride.
* dwarf.c (process_extended_line_op): Add cases for HP extensions to the line ops.
  Mention if an unknown op code is in the user defined range.
  (decode_location_expression): Add cases for HP extensions, the DW_OP_GNU_uninit extension and the DW_OP_call_frame_cfa and DW_OP_bit_piece DWARF3 operators.
  (read_and_display_attr): Correct list of attributes which can reference a location list.
  (read_and_display_attr_value): Add cases for DWARF3 values and HP extensions.
  Correct list of attributes which can reference a location list.
  (get_AT_name): Add cases for DWARF3 values and HP and PGI extensions.