uml: miscellaneous code cleanups

Code tidying -
	the pid field of struct irq_fd isn't used, so it is removed
     	os_set_fd_async needed to read flags before changing them, it
doesn't need a pid passed in because it can call getpid itself, and a
block of unused code needed deleting
	os_get_exec_close was unused, so it is removed
	ptrace_child called _exit for historical reasons which are no
longer valid, so just calls exit instead

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
index ba11ccd..91587f8 100644
--- a/arch/um/kernel/irq.c
+++ b/arch/um/kernel/irq.c
@@ -107,10 +107,9 @@
 	struct pollfd *tmp_pfd;
 	struct irq_fd *new_fd, *irq_fd;
 	unsigned long flags;
-	int pid, events, err, n;
+	int events, err, n;
 
-	pid = os_getpid();
-	err = os_set_fd_async(fd, pid);
+	err = os_set_fd_async(fd);
 	if (err < 0)
 		goto out;
 
@@ -127,7 +126,6 @@
 				     .fd 		= fd,
 				     .type 		= type,
 				     .irq 		= irq,
-				     .pid  		= pid,
 				     .events 		= events,
 				     .current_events 	= 0 } );