Make AARCH64 harder, better, faster, stronger

- Perform some housekeeping on scalar math function code
- Import ARM's Optimized Routines for SIMD string processing
- Upgrade to latest Chromium zlib and enable more SIMD optimizations

third_party/zlib/adler32_simd.inc

@@ -0,0 +1,15 @@
+/* adler32_simd.h
+ *
+ * Copyright 2017 The Chromium Authors
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the Chromium source repository LICENSE file.
+ */
+
+#include "libc/inttypes.h"
+#include "libc/limits.h"
+#include "libc/literal.h"
+#include "third_party/zlib/zconf.h"
+#include "third_party/zlib/zutil.internal.h"
+
+uint32_t ZLIB_INTERNAL adler32_simd_(uint32_t adler, const unsigned char *buf,
+                                     z_size_t len);