dwarf2out.c: Revert most of 2000-11-25 and 2001-01-24 changes.
* dwarf2out.c: Revert most of 2000-11-25 and 2001-01-24 changes.
(LN_PROLOG_AS_LABEL, LN_PROLOG_END_LABEL): New.
(size_of_line_prolog): Remove.
(output_line_info): Compute prologue size via label difference.
(lookup_filename): Return "unspecified" for <internal> and <built-in>.
* configure.in (HAVE_AS_DWARF2_DEBUG_LINE): Require that the
assembler error when redefining file numbers.
* config.in, configure: Rebuild.