zlib: add neon optimizations

This introduces arm/neon optimizations to zlib.

The first two patches are a neon optimization relating to zlib's
inflate function. They increase decompression speed. It has been
shipping in Chromimum since release 62 (Oct. 2017). The patches have
been pulled from a PR to zlib upstream: madler/zlib#345.

Patches 003 and 004 have been pulled from Fedora Core's aarch64 zlib
package. They improve zlib compression speed and have been there for
4 months.

Patch 005 is pulled from a PR to zlib upstream. madler/zlib#251. It's
been shipping in Chromium since release 63, and increases
decompression speed.

Patch 006 is my own to allow 005 to merge without conflict with the
previous patches.

Signed-off-by: Ian Leonard <antonlacon@gmail.com>

packages/compress/zlib/package.mk

@@ -14,3 +14,7 @@ PKG_SECTION="compress"
 PKG_SHORTDESC="zlib: A general purpose (ZIP) data compression library"
 PKG_LONGDESC="zlib is a general purpose data compression library. All the code is thread safe. The data format used by the zlib library is described by RFCs (Request for Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format)."
 PKG_TOOLCHAIN="cmake-make"
+
+if target_has_feature neon; then
+  PKG_CMAKE_OPTS_TARGET="-DARM_NEON=on"
+fi