[krbdev.mit.edu #6125] krb5_cccol_lock/unlock should not have hardcoded mutex names

[Justin Anderson via RT]

e.g. krb5int_cc_file_mutex, krb5int_mcc_mutex, krb5int_krcc_mutex should not be explicitly 
named in the cccol locking functions. 

It would be less fragile to add pertype lock and unlock calls to each cache type's ops vector and 
make krb5_cccol_lock/unlock iterate the types.