This reverts commit 2ce6a7eb.

the Requires list contained a trailing comma if liburcu wasn't present,
pkg-config as of 0.29 treats this as an error, resulting in failed
package --cflags and --atleast-version lookups

this change treats libdnssec as mandatory, and extras must be prefixed with
comma inside the expanded variables

keymgr: add support for upgrade



See merge request !480

UDP socket limit

closes #442

See merge request !479

- '%s' zone file name formatter always removes trailing dot
- 'reload' event is renamed to 'load' event

CID #1343647 #1343646

Revert another useless change related to version.h wizardry.