Handle gdb.LazyString in DAP

Andry pointed out that the DAP code did not properly handle
gdb.LazyString results from a pretty-printer, yielding:

    TypeError: Object of type LazyString is not JSON serializable

This patch fixes the problem, partly with a small patch in varref.py,
but mainly by implementing tp_str for LazyString.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>


6 files changed