New vCtrlC packet, non-stop mode equivalent of \003

New vCtrlC packet, non-stop mode equivalent of \003

There's currently no non-stop equivalent of the all-stop ^C (\003)
"packet" that GDB sends when a ctrl-c is pressed while a foreground
command is active.  There's vCont;t, but that's defined to cause a
"signal 0" stop.

This fixes many tests that type ^C, when testing with extended-remote
with "maint set target-non-stop on".  E.g.:

 Continuing.
 talk to me baby
 PASS: gdb.base/interrupt.exp: process is alive
 a
 a
 PASS: gdb.base/interrupt.exp: child process ate our char
 ^C
 [Thread 22730.22730] #1 stopped.
 0x0000003615ee6650 in __read_nocancel () at ../sysdeps/unix/syscall-template.S:81
 81      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
 (gdb) FAIL: gdb.base/interrupt.exp: send_gdb control C
 p func1 ()

gdb/
2015-11-30  Pedro Alves  <palves@redhat.com>

	* NEWS (New remote packets): Mention vCtrlC.
	* remote.c (PACKET_vCtrlC): New enum value.
	(async_remote_interrupt): Call target_interrupt instead of
	target_stop.
	(remote_interrupt_as): Remove 'ptid' parameter.
	(remote_interrupt_ns): New function.
	(remote_stop): Adjust.
	(remote_interrupt): If the target is in non-stop mode, try
	interrupting with vCtrlC.
	(initialize_remote): Install set remote ctrl-c packet.

gdb/doc/
2015-11-30  Pedro Alves  <palves@redhat.com>

	* gdb.texinfo (Bootstrapping): Add "interrupting remote targets"
	anchor.
	(Packets): Document vCtrlC.

gdb/gdbserver/
2015-11-30  Pedro Alves  <palves@redhat.com>

	* server.c (handle_v_requests): Handle vCtrlC.