to be compiled in

The problem was that on a statically built server an attempt to create
a UDF resulted in a different, but reasonable error ("Can't open shared
library" instead of "UDFs are unavailable with the --skip-grant-tables
option"), which caused a failure for the test case for bug #32020.

Fixed by moving the test case for bug #32020 from skip_grants.test to a
separate test to ensure that it is only run when the server is built
with support for dynamically loaded libraries.