um: start switching the references to host mcontext_t to its userland type

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/um/sys-x86/stub_segv.c b/arch/um/sys-x86/stub_segv.c
index f62771c..bd2eaf6 100644
--- a/arch/um/sys-x86/stub_segv.c
+++ b/arch/um/sys-x86/stub_segv.c
@@ -12,7 +12,7 @@
 {
 	struct ucontext *uc = p;
 
-	GET_FAULTINFO_FROM_SC(*((struct faultinfo *) STUB_DATA),
+	GET_FAULTINFO_FROM_MC(*((struct faultinfo *) STUB_DATA),
 			      &uc->uc_mcontext);
 	trap_myself();
 }