downgrade .debug_line to DWARFv4
downgrade .debug_line to DWARFv4

apparently gdb 8.3.1 which is still a commonly distributed version of gdb,
does not support v5.

raulgrell/zig,zig-lang/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,andrewrk/zig