Replace gssrpc tests with a Python script

Replace gssrpc tests with a Python script

Replace the dejagnu RPC test framework with a short Python script to
do the same tests as fullrun.exp and gsserr.exp.  Modify the server
test program to facilitate use by k5test.py.

expire.exp, together with a comment in the client test program, was
designed to test a libdb2 btree bug via the gssrpc server-side
authentication code.  That code was subsequently changed not to use
libdb2, before it was merged into the main krb5 tree (in revision 1.23
of svc_auth_gssapi.c, according to the changelog removed in commit
2a43d772be1e45faa8e488d436b6e867371563fb).  Remove the comment and do
not replace that test sequence.