librados: Only public API symbols from the shared library

The librados shared library was previously exporting all
symbols.  librados public API methods are now explicitly
exported and all other symbols are hidden.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>
It would be reassuring to have a minimal test script run by make check that runs all bin_DEBUGPROGRAMS, just to have the --help. That would validate there is no dynamic linking issue.