* cc_file.c (struct _krb5_fcc_data): Add new mutex disk_file_lock and flag

* cc_file.c (struct _krb5_fcc_data): Add new mutex disk_file_lock and flag
file_is_locked.
(krb5_fcc_close_file): Unlock the mutex and clear the flag.
(krb5_fcc_open_file): Acquire the mutex before locking the file, and set the
flag after.
(krb5_fcc_resolve): Initialize the new mutex and flag.
(krb5_fcc_generate_new): Initialize both mutexes and the flag.
(dereference): Destroy the new mutex.

Also, get rid of some unused variables.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@16667 dc483132-0cff-0310-8789-dd5450dbe970