configure: hook up minilzo to the libsigrok build, reflect its version

configure: hook up minilzo to the libsigrok build, reflect its version

Add the minilzo/ directory to the list of source files for the libsigrok
build. Have the minilzo library use the project's config.h file, extend
the set of autoconf checks. This approach follows the documentation in
the README.LZO file. It avoids the dependency on an external library and
its version or configuration.

Reflect the minilzo version in the libsigrok version output. The example
application which ships with the library suggests that failed init calls
typically originate from compile issues. Present the same error message
to sigrok users as the example application does.