b64_encode and decode

I require base64 or some similar encoding scheme from a C language
extension and need it to be as fast as reasonably possible. In
src/backend/utils/adt/encode.c there are functions b64_encode and
b64_decode which would be ideal but these are defined static and so are
not available to my code.

I know I could call these functions indirectly by calling binary_ecncode
through DirectFunctionCalln() but this is a whole lot more complexity
and overhead than I'd like.

I note that /contrib/pgcrypto/pgp-armor.c appears to have its own copies
of these 2 functions and now I have elected to do the same.

So, would there be any chance of redefining the base64 functions in
encode.c as extern to eliminate this redundancy?

__
Marc