Build hcrypto with libtool

XXX changes LIB_hcrypto in hacky ways.

Or rather, with lwptool, since we need a LWP version as well as
the various pthreaded versions.

The previous version was the initial version, 1.1, but since we're
switching to libtool, bump the version to 2.0 just to be safe.

Libtool abstracts away the extra logic that had previously been needed
to build different copies of rand-fortuna for the pthreaded and LWP
libraries.

Change-Id: Ibc530a1fa4baa7a38b44eb3e0719e1905a6fe269
Link aklog against LIB_hcrypto

This was the last place where libafshcrypto.a was explicitly referenced,
preventing the use of an out-of-tree hcrypto library.

We will continue to need to build the in-tree code to produce a
libafshcrypto_lwp.a library for use in LWP applications, until we
do not have any more LWP applications, but some systems (such as
Debian) have a desire to avoid bundled libraries, so we should
facilitate the use of an external libhcrypto where possible.

Many consumers of libafshcrypto_lwp.a will be removed when the
LWP versions of various modules are removed after 1.8 is branched.

Change-Id: I23049866caae9c16ffb2ec32c5e7b058465a26ba
Allow external hcrypto

Put the configure checks into a separate file in src/cf, following
the same general structure as the roken checks.

Allow explicitly requesting the internal version, or checking
what's in the default paths, or providing a specific hcrypto root
or lib/include dirs for Debian compatibility.

We must still always compile libafshcrypto_lwp.a for use by LWP
binaries, from the bundled sources, but other binaries will use
the system version.

Change-Id: Idcba1418a19a7b562335524c911d69dc84268177