Fix TSan report in Kerberos

[alexey-milovidov]

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This closes #48415

prof_int.h:

/*
 * This is the structure which stores the profile information for a
 * particular configuration file.
 *
 * Locking strategy:
 * - filespec, fslen are fixed after creation
 * - refcount and next should only be tweaked with the global lock held
 * - other fields can be tweaked after grabbing the in-struct lock
 */
struct _prf_data_t {