um: kill includes of sysdep/sigcontext.h from stuff built with kernel headers

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/kernel/signal.c

@@ -11,7 +11,6 @@
 #include <asm/unistd.h>
 #include "frame_kern.h"
 #include "kern_util.h"
-#include <sysdep/sigcontext.h>
 
 EXPORT_SYMBOL(block_signals);
 EXPORT_SYMBOL(unblock_signals);

arch/um/kernel/trap.c

@@ -14,7 +14,6 @@
 #include "kern_util.h"
 #include "os.h"
 #include "skas.h"
-#include "sysdep/sigcontext.h"
 
 /*
  * Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by