* remote-utils.c (prepare_resume_reply): If requested, don't
output "thread:TID" in the T stop reply.
* server.c (disable_packet_vCont, disable_packet_Tthread)
(disable_packet_qC, disable_packet_qfThreadInfo): New globals.
(handle_query): If requested, disable support for qC, qfThreadInfo
and qsThreadInfo.
(handle_v_requests): If requested, disable support for vCont.
(gdbserver_show_disableable): New.
(main): Handle --disable-packet and --disable-packet=LIST.
* server.h (disable_packet_vCont, disable_packet_Tthread)
(disable_packet_qC, disable_packet_qfThreadInfo): Declare.