Updated to v4.4.1 kernel headers.

Small modifications needed to allow compilation with the new headers:

- Manually modify bionic/libc/kernel/uapi/asm-mips/asm/siginfo.h to
  remove the uapi from the include.
- PR_XXX defines are now available for mips, so remove the definition
  from linker_mips.cpp.

Bug: 23789423
Change-Id: I6dc8a03b012426d3a937db15cb24d3a50fab5a8c
diff --git a/libc/kernel/uapi/asm-arm64/asm/ucontext.h b/libc/kernel/uapi/asm-arm64/asm/ucontext.h
new file mode 100644
index 0000000..edb9155
--- /dev/null
+++ b/libc/kernel/uapi/asm-arm64/asm/ucontext.h
@@ -0,0 +1,33 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   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 _UAPI__ASM_UCONTEXT_H
+#define _UAPI__ASM_UCONTEXT_H
+#include <linux/types.h>
+struct ucontext {
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+  unsigned long uc_flags;
+  struct ucontext * uc_link;
+  stack_t uc_stack;
+  sigset_t uc_sigmask;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+  __u8 __linux_unused[1024 / 8 - sizeof(sigset_t)];
+  struct sigcontext uc_mcontext;
+};
+#endif
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */