Notably, there's a test to make sure that it round-trips with
OpenSSL, if OpenSSL is enabled.

We only ever need this to get us a DH ephemeral key object,
so make a function that does just that.

This is comparatively straightforward too, except for a couple of
twists:

   * For as long as we're building with two crypto libraries, we
     want to seed _both_ their RNGs, and use _both_ their RNGs to
     improve the output of crypto_strongest_rand()

   * The NSS prng will sometimes refuse to generate huge outputs.
     When it does, we stretch the output with SHAKE.  We only need
     this for the tests.

This was a fairly straightforward port, once I realized which layer
I should be calling into.

We need this in our unit tests, since otherwise NSS will notice
we've forked and start cussing us out.

I suspect we'll need a different hack for daemonizing, but this
should be enough for tinytest to work.

This is largely conjectural, based on online documentation for NSS
and NSPR.

These are now part of crypto_init.c.  The openssl-only parts now
live in crypto_openssl_mgt.c.

I recommend reviewing this patch with -b and --color-moved.

When it is set, include the NSS headers and libraries as
appropriate.  Doesn't actually use them yet, though.

That place is git-revision.c; git-revision.c now lives in lib/log.

Also fix the compilation rules so that all object files that need
micro-revision.i depend on it.

Fun fact: these files used to be called log.[ch] until we ran into
conflicts with systems having a log.h file.  But now that we always
include "lib/log/log.h", we should be fine.

(Bugfixes on bugs that have never been in a released version don't
need a changes file.)

(Almost none of Tor should actually need to touch the platform resolver.)

This lets us cut the dependency from address.c to resolve.c: the
address.c module now has no paths to the libc resolver in it.

This function has a nasty API, since whether or not it invokes the
resolver depends on whether one of its arguments is NULL.  That's a
good way for accidents to happen.

This patch incidentally makes tor-resolve support socks hosts on
IPv6.