Update to kernel headers v4.12.3.

Test: Built angler.
Change-Id: Icbcf4fac2334de8409b049ed7a3b4c24b4e98ce9
diff --git a/libc/kernel/uapi/linux/elf.h b/libc/kernel/uapi/linux/elf.h
index e8f8bb4..8aa1011 100644
--- a/libc/kernel/uapi/linux/elf.h
+++ b/libc/kernel/uapi/linux/elf.h
@@ -345,6 +345,8 @@
 #define NT_S390_TDB 0x308
 #define NT_S390_VXRS_LOW 0x309
 #define NT_S390_VXRS_HIGH 0x30a
+#define NT_S390_GS_CB 0x30b
+#define NT_S390_GS_BC 0x30c
 #define NT_ARM_VFP 0x400
 #define NT_ARM_TLS 0x401
 #define NT_ARM_HW_BREAK 0x402
@@ -353,6 +355,7 @@
 #define NT_METAG_CBUF 0x500
 #define NT_METAG_RPIPE 0x501
 #define NT_METAG_TLS 0x502
+#define NT_ARC_V2 0x600
 typedef struct elf32_note {
   Elf32_Word n_namesz;
   Elf32_Word n_descsz;