link clients dynamically in RPMs

Currently in RPMs (at least, may be in DEB too), all clients are linked statically. They're much larger than they should be and library bugs cannot be fixed by upgrading the libraries.

We need to link clients dynamically with libmysql.so and libmysqld.so

The problem is that our clients use mysys and string and dbug. And libmysqlclient uses all that. But dynamic library doesn't export these symbols (they aren't part of the client-server API).