Add x86_64 to the bionic headers.

Manual changes:

  cpp.py: cope with macros that refer to other macros.

  defaults.py: x86 no longer always implies __i386__; use __i386__ to replace
  the kernel CONFIG_X86_32 flag.

  asm/page.h: the upstream page.h isn't a uapi header and no longer includes
  the stuff we were using it for. Let's just have our own static file, since
  it's the same for all our architectures (both 32- and 64-bit).

  sys/select.h: we used to use the various FD_SET-related macros from the
  kernel header files, but they've gone. Adjust by adding trivial equivalent
  definitions.

Automated changes:

  libc/kernel/arch-x86, libc/kernel/common: regenerated from
  external/kernel-headers.

Change-Id: I84fc0ed52dc742e043b4ae300fd3b58ee99b7fcd

libc/kernel/common/asm-generic/bitsperlong.h

@@ -0,0 +1,25 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ***   To edit the content of this header, modify the corresponding
+ ***   source file (e.g. under external/kernel-headers/original/) then
+ ***   run bionic/libc/kernel/tools/update_all.py
+ ***
+ ***   Any manual change here will be lost the next time this script will
+ ***   be run. You've been warned!
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef __ASM_GENERIC_BITS_PER_LONG
+#define __ASM_GENERIC_BITS_PER_LONG
+#ifndef __BITS_PER_LONG
+#define __BITS_PER_LONG 32
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#endif
+#endif