There is no longer an external (or stable) interface for libopensc.
Linking this program with an existing version of libopensc that is
pre-installed in the system library paths is not practical.
However, a specific snapshot of the OpenSC source code is embedded
here as a Git submodule (and included in the source distributions).
Build libopensc from this and statically link it into this program.
(Options such as '--enable-openpace' that are passed to ./configure
will be forwarded to control the build configuration of libopensc.)
Remove code that existed for compatibility when dynamically linking
with older versions of libopensc.
