PR c++/12824:

	PR c++/12824:
	* NEWS: Update.
	* breakpoint.c (enum exception_event_kind) <EX_EVENT_RETHROW>:
	New constant.
	(classify_exception_breakpoint): New function.
	(print_it_exception_catchpoint, print_one_exception_catchpoint)
	(print_mention_exception_catchpoint)
	(print_recreate_exception_catchpoint, handle_gnu_v3_exceptions)
	(catch_exception_command_1): Handle "rethrow" catchpoint.
	(catch_rethrow_command): New function.
	(_initialize_breakpoint): Add "catch rethrow" command.
gdb/doc
	* gdb.texinfo (Set Catchpoints): Reorganize exception
	catchpoints.  Document "catch rethrow".
	(Debugging C Plus Plus): Mention "catch rethrow".
gdb/testsuite
	* gdb.cp/exception.exp: Add "catch rethrow" tests.