libdw: Translate DW_LANG_Algol68 to DW_LNAME_Algol68 with lversion 1978

libdw: Translate DW_LANG_Algol68 to DW_LNAME_Algol68 with lversion 1978

1978 is the year of the publication of the Revised Report that defines
the revised language. And this is the version set by gcc a68. So when
we see DW_LANG_Algol68 we translate it to DW_LNAME_Algol68 with
lversion set to 1978 to match gcc a68.

	* libdw/dwarf_srclang.c (srclang_to_language): Set lversion to
        1978 for DW_LANG_Algol68.

Signed-off-by: Mark Wielaard <mark@klomp.org>