Add arch-x86_64/include/machine.

This is basically the other half of I5de76f6c46ac87779f207d568a86bb453e2414de
from Pavel Chupin <pavel.v.chupin@intel.com>, but taking the exact upstream
_types.h instead of the modified version. (I was confused when I suggested
otherwise.)

I've also cleaned up the internal_types.h situation; we weren't gaining
anything from these empty files, and there is no upstream internal_types.h
for x86_64.

Change-Id: I802a9a6a8df1c979e820659212c75a47c2ef392e
diff --git a/libc/arch-x86_64/include/machine/setjmp.h b/libc/arch-x86_64/include/machine/setjmp.h
new file mode 100644
index 0000000..01d6066
--- /dev/null
+++ b/libc/arch-x86_64/include/machine/setjmp.h
@@ -0,0 +1,21 @@
+/*	$OpenBSD: setjmp.h,v 1.1 2004/01/28 01:39:39 mickey Exp $	*/
+/*	$NetBSD: setjmp.h,v 1.1 2003/04/26 18:39:47 fvdl Exp $	*/
+
+/*
+ * machine/setjmp.h: machine dependent setjmp-related information.
+ * These are only the callee-saved registers, code calling setjmp
+ * will expect the rest to be clobbered anyway.
+ */
+
+#define _JB_RBX		0
+#define _JB_RBP		1
+#define _JB_R12		2
+#define _JB_R13		3
+#define _JB_R14		4
+#define _JB_R15		5
+#define _JB_RSP		6
+#define _JB_PC		7
+#define _JB_SIGFLAG	8
+#define _JB_SIGMASK	9
+
+#define	_JBLEN	11		/* size, in longs, of a jmp_buf */