Clean up the arm64 setjmp.

Note that this doesn't address the fact that we don't save/restore the
real-time signals. But it does let us pass the tests we currently fail.

Bug: 16918359
Change-Id: I063a6926164289a71026a412da7f5dd2ca9a74b3
diff --git a/libc/arch-arm64/include/machine/setjmp.h b/libc/arch-arm64/include/machine/setjmp.h
index 1c237da..27c2fe5 100644
--- a/libc/arch-arm64/include/machine/setjmp.h
+++ b/libc/arch-arm64/include/machine/setjmp.h
@@ -26,48 +26,5 @@
  * SUCH DAMAGE.
  */
 
-/*
- * machine/setjmp.h: machine dependent setjmp-related information.
- */
-
-/* _JBLEN is the size of a jmp_buf in longs(64bit on AArch64) */
+/* _JBLEN is the size of a jmp_buf in longs (64bit on AArch64) */
 #define _JBLEN 32
-
-/* According to AARCH64 PCS document we need to save the following
- * registers:
- *
- * Core     x19 - x30, sp (see section 5.1.1)
- * VFP      d8 - d15 (see section 5.1.2)
- *
- * NOTE: All the registers saved here will have 64bit vales (except FPSR).
- *       AAPCS mandates that the higher part of q registers does not need to
- *       be saveved by the callee.
- */
-
-/* The structure of jmp_buf for AArch64:
- *
- * NOTE: _JBLEN is the size of jmp_buf in longs(64bit on AArch64)! The table
- *      below computes the offsets in words(32bit).
- *
- *  word        name            description
- *  0       magic           magic number
- *  1       sigmask         signal mask (not used with _setjmp / _longjmp)
- *  2       core_base       base of core registers (x19-x30, sp)
- *  28      float_base      base of float registers (d8-d15)
- *  44      reserved        reserved entries (room to grow)
- *  64
- *
- *
- *  NOTE: The instructions that load/store core/vfp registers expect 8-byte
- *        alignment. Contrary to the previous setjmp header for ARM we do not
- *        need to save status/control registers for VFP (it is not a
- *        requirement for setjmp).
- */
-
-#define _JB_MAGIC       0
-#define _JB_SIGMASK     (_JB_MAGIC+1)
-#define _JB_CORE_BASE   (_JB_SIGMASK+1)
-#define _JB_FLOAT_BASE  (_JB_CORE_BASE + (31-19+1)*2)
-
-#define _JB_MAGIC__SETJMP   0x53657200
-#define _JB_MAGIC_SETJMP    0x53657201