Move (and sometimes add) #include <config.h> at the top of
all *.c files.

Remove all #include ["<]config.h[">] from headers files.

Change-Id: I1df07602d0240affd95e12fccd122558300d2145

* Node and rrset now must use new API for changing owner (*_set_owner())
* Every structure that stores pointer to dname must retain reference to it
* Destructors in rrset now release all stored dnames, obsoletes parameters: free_owner
* Destructor in rdata_deep_free has obsolete parameter: free_all_dnames
* Fixed some direct data manipulation
* Some code readability improvements
* To do:
 * Reference counting in zparser is disabled for now, implement correctly.
 * Remove obsolete parameters.
 * Destructors should have no extra parameters.
* Tested with server startup, querying and AXFR client/server

Commit refs #993.

GCC builtins are used for atomic add/sub and fetch.
May be extended with assembly for other compilers later.

Commit refs #993.