auth: Minor code cleanup - fix parameter type

Removed all the "enum foo;" declarations. They didn't seem to be very standard. Old gcc versions warn about them and C++ code doesn't like them.

auth: Fixed crash at deinit. --HG-- branch : HEAD

Initial commit for config rewrite. --HG-- branch : HEAD

Changed .h ifdef/defines to use <NAME>_H format. --HG-- branch : HEAD

Removed unneeded enum declarations. --HG-- branch : HEAD

Added "bool" type and changed all ints that were used as booleans to bool. --HG-- branch : HEAD

Fixes and cleanups to credentials handling. Also fixed auth caching to work more correctly in case of internal failures. --HG-- branch : HEAD

Added state variable for auth_request and several assertions to make sure the state is always valid. Fixed assert crash when a user having cached passdb entry expired tried to authenticate. --HG-- branch : HEAD

Fallback to using expired records from auth cache if database lookups fail. --HG-- branch : HEAD

Moved cache handling from sql/ldap-specific code to generic auth-request code. Did some small optimizations on the way. --HG-- branch : HEAD

Added simple LRU cache for auth requests. Currently only for sql passdb. --HG-- branch : HEAD