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-generic/unistd.h b/libc/kernel/uapi/asm-generic/unistd.h
index d7ac6c2..635a123 100644
--- a/libc/kernel/uapi/asm-generic/unistd.h
+++ b/libc/kernel/uapi/asm-generic/unistd.h
@@ -377,8 +377,13 @@
 #define __NR_memfd_create 279
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define __NR_bpf 280
+#define __NR_execveat 281
+#define __NR_userfaultfd 282
+#define __NR_membarrier 283
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+#define __NR_mlock2 284
 #undef __NR_syscalls
-#define __NR_syscalls 281
+#define __NR_syscalls 285
 #ifdef __ARCH_WANT_SYSCALL_NO_AT
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define __NR_open 1024