Update to v4.19 kernel headers.

Test: Builds and boots.
Change-Id: I99a9ed79666e143b47f02ca4e59eed94f69b7e4a
(cherry picked from commit a981e2e52e2e95a65fa9c9b6fb16dcb4c83dd576)
diff --git a/libc/kernel/uapi/asm-arm64/asm/auxvec.h b/libc/kernel/uapi/asm-arm64/asm/auxvec.h
index 74fca55..4735fd5 100644
--- a/libc/kernel/uapi/asm-arm64/asm/auxvec.h
+++ b/libc/kernel/uapi/asm-arm64/asm/auxvec.h
@@ -19,5 +19,6 @@
 #ifndef __ASM_AUXVEC_H
 #define __ASM_AUXVEC_H
 #define AT_SYSINFO_EHDR 33
-#define AT_VECTOR_SIZE_ARCH 1
+#define AT_MINSIGSTKSZ 51
+#define AT_VECTOR_SIZE_ARCH 2
 #endif