Make _struct_sockaddr_u_impl() tapset function output more consistent.

Make _struct_sockaddr_u_impl() tapset function output more consistent.

* tapset/linux/aux_syscalls.stp (_struct_sockaddr_u_impl): Make output
  more consistent. When _struct_sockaddr_u_impl() succeeds, it returns
  '{INFO}'. When it failed, it returned '[...]'. Now when it fails it
  returns '{...}'.
* testsuite/systemtap.syscall/bind.c: Updated expected test output.
* testsuite/systemtap.syscall/connect.c: Updated expected test output.
* testsuite/systemtap.syscall/sendto.c: Updated expected test output.