* gdbserver/remote-utils.c (remote_open): Set gdbserver as "owner"

* gdbserver/remote-utils.c (remote_open): Set gdbserver as "owner"
of SIGIO.
(input_interrupt): Don't block on read, in case we got redundant
SIGIO.  Don't gripe about redundant SIGIO.
* gdbserver/low-hppabsd.c (mywait): Use waitpid().  Enable SIGIO
handler while waiting.
* gdbserver/low-linux.c (mywait): Likewise.
* gdbserver/low-nbsd.c (mywait): Likewise.
* gdbserver/low-sparc.c (mywait): Likewise.