Export FcConfig{G,S}etRescanInverval from .so, mark as deprecated.

Export FcConfig{G,S}etRescanInverval from .so, mark as deprecated.

These two names are typos of the correct names. Instead of simply changing
them, the correct thing to do is leave them in the library, add the correct
functions and mark them as deprecated so any source packages will be updated.

This requires bumping the minor version of the library (for adding APIs)
instead of bumping the major version of the library (for removing APIs).