Remove one version definition

This at least lets me remove one version definition from the
Configfile, but there's still the one in there for pkg-config.  I'll n
eed to muck around with ppkg-config to fix that...
Don't double-define PCONFIGURE_VERSION

Looks like once again I forgot to bootstrap.  Whoops!
Remove a circular pkg-config dependency

This caused the generated pkg-config files to depend on themselves.
This wasn't actually triggered because the code wasn't actually
checking for dependencies in this particular manner, but this should
fix it.
Support "-S..." in pkg-config

The pkg-config support is still really a gaint sed script.  This loads
the sed from a file (dynamically) rather than baking it into the
Makefile.  The idea is that I can now build pkg-config files that have
dependencies that are satisfied by the Makefile, as opposed to by
pconfigure.

This is all part of my quest to only define the version number of
pconfigure in a single place and have everything else auto-generated.
Generate dependencies for link-only libraries

It turns out that the dependency check function was never actually
being called if I had a link-only shared library.  I guess nothing was
testing this particular functionality, but it turns out that it's
possible for pkg-config files to trigger this.
Define pkg-config version in terms of C version

This removes the last extra definition of the version number.  It's
now defined in a single place and it's checked during the build
process.