This is the same memcpy()-in-hot-path xxHash problem as described
in community/xxhash commit message.

The bug makes "zstd -1" or "zstd -t" ~15% slower on x86_64 though
higher levels (>= 9) are almost unaffected.

Other aport changes:
 - make sure zlib/lzma/lz4 support is not compiled in automatically
   (status quo, just make it explicit);
 - re-enable armv7 since it is certainly well-supported by upstream,
   was disabled by some script in the first place and should not be
   affected by "Bus error" (i.e. some alignment problem) mentioned in
   commit 2bae66907...
 - use faster and shorter "make check" (unlike extensive "make test")
   on arm* builders.

This makes it possible to provide armv7 as additional architecture in
Alpine, next to armhf. See the discussion in this ML thread:
<https://lists.alpinelinux.org/alpine-devel/6271.html>

It's done by adding armv7 next to armhf in the arch line and also
!armv7 where the arch line said !armhf. The following script was used:

Applied 2 upstream patches that fix a behavior when stdin
is not a tty.

We force -O2 over system configured -Os since it seem to have significant
impact on performance.

We also split out -libs and -static subpackage.