r6271: Don't zero the cli_credentials structure - instead allow valgrind to

r6271: Don't zero the cli_credentials structure - instead allow valgrind to
track the use of un-initialised values.

This change will require a recompile from clean, as the enum
describing the status of each element now has a default of
CRED_UNINITIALISED.

Andrew Bartlett
(This used to be commit 83c2eb806d43f588bd06336aa7e2dbdc00dc2c67)