Because `master` branch seems incompatible, or at least with breaking
changes that cause the test to fail.

Because that's the minimum required by hexpm server.

- Update expected cowlib version in core-query tests
- Add -k flag to lockf in core/deps.mk to prevent concurrency issues
during rebar3 bootstra

Thanks Ilya Khaprov for the fix.

On FreeBSD, libsodium's `sodium.h` header is installed in
`/usr/local/local`. The Makefile already adds
`/usr/local/include/sodium` to the compiler's `-I` search path, but it
doesn't cover the FreeBSD case.

This patch adds `-I /usr/local/include` to the CFLAGS on the make(1)
command line to let libsalty2's Makefile pick it up. This fixes the
build on FreeBSD.

Its Makefile called sed(1) in a way that was only compatible with GNU
sed. As a consequence, the build failed with BSD sed.

Now, the test case fetches dependencies and patches `reloader`'s
Makefile to use a sed(1) script compatible with both implementations of
sed(1).

This is the standard name and is available everywhere, unlike "netcat".

If `V=...` is set on the command line to increase verbosity while
debugging, the first grep(1) command will also catch the debug output of
make(1) which contains the executed command line and thus mentions
"hello".

The fixed grep(1) command line explicitly grep for a line starting with
"hello".

... instead of https://github.com/hypernumbers/hypernumbers which is no
longer available apparently.