Hello,

Using 4 as the DWARF_VERSION_DEFAULT value for VxWorks observably
still hangs recent system debuggers on tbreak for some contructs,
and downgrading to 3 improves the situation.

Committing to mainline shortly.

Cheers,

Olivier

2022-03-06  Olivier Hainque  <hainque@adacore.com>

gcc/
        * config/vxworks.h (DWARF_VERSION_DEFAULT): Adjust from
        4 to 3 for VxWorks >= 7.