Use safe output formats for strings that are not null terminated.


sql/item_func.cc:
  Use "%*.s" rather than "%s" format.
sql/protocol.cc:
  Use "%*.s" rather than "%s" format.
sql/sql_test.cc:
  Improve output from print_where()
   - output (nil) predicate if predicate is null
   - also output pointer value, for tracing of assignment and copying of predicates
sql/sql_view.cc:
  Use "%*.s" rather than "%s" format.