uml: remove code made redundant by CHOOSE_MODE removal

This patch makes a number of simplifications enabled by the removal of
CHOOSE_MODE.  There were lots of functions that looked like

	int foo(args){
		foo_skas(args);
	}

The bodies of foo_skas are now folded into foo, and their declarations (and
sometimes entire header files) are deleted.

In addition, the union uml_pt_regs, which was a union between the tt and skas
register formats, is now a struct, with the tt-mode arm of the union being
removed.

It turns out that usr2_handler was unused, so it is gone.

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/os-Linux/trap.c b/arch/um/os-Linux/trap.c
index b17f546..e87fb536 100644
--- a/arch/um/os-Linux/trap.c
+++ b/arch/um/os-Linux/trap.c
@@ -7,15 +7,10 @@
 #include <signal.h>
 #include "kern_util.h"
 #include "os.h"
-#include "mode.h"
 #include "longjmp.h"
 
-void usr2_handler(int sig, union uml_pt_regs *regs)
-{
-}
-
 /* Initialized from linux_main() */
-void (*sig_info[NSIG])(int, union uml_pt_regs *);
+void (*sig_info[NSIG])(int, struct uml_pt_regs *);
 
 void os_fill_handlinfo(struct kern_handlers h)
 {
@@ -28,7 +23,6 @@
 	sig_info[SIGIO] = h.sigio_handler;
 	sig_info[SIGVTALRM] = h.timer_handler;
 	sig_info[SIGALRM] = h.timer_handler;
-	sig_info[SIGUSR2] = usr2_handler;
 }
 
 void do_longjmp(void *b, int val)