[gdb] Handle ^C in ~scoped_remote_fd

[gdb] Handle ^C in ~scoped_remote_fd

While reviewing "catch (...)" uses I came across:
...
	try
	  {
	    fileio_error remote_errno;
	    m_remote->remote_hostio_close (m_fd, &remote_errno);
	  }
	catch (...)
	  {
	    /* Swallow exception before it escapes the dtor.  If
	       something goes wrong, likely the connection is gone,
	       and there's nothing else that can be done.  */
	  }
...

This also swallows gdb_exception_quit and gdb_exception_forced_quit.  I don't
know whether these can actually happen here, but if not it's better to
accommodate for the possibility anyway.

Fix this by handling gdb_exception_quit and gdb_exception_forced_quit
explicitly.

It could be that "catch (...)" should be replaced by
"catch (const gdb_exception &)" but that depends on what kind of exception
remote_hostio_close is expected to throw, and I don't know that, so I'm
leaving it as is.

Tested on aarch64-linux.

Approved-By: Tom Tromey <tom@tromey.com>