build: make manpage generation reproducible
build: make manpage generation reproducible

pod2man will insert a date in the footer of the manpage. By default,
it takes this value from the mtime of the input file. But this makes
it non-deterministic in that another build may produce other results.
By setting it to always be the date of the latest release we make it
deterministic.

iwconfig/svtplay-dl,selepo/svtplay-dl,selepo/svtplay-dl,iwconfig/svtplay-dl,OakNinja/svtplay-dl,spaam/svtplay-dl,olof/svtplay-dl,spaam/svtplay-dl,dalgr/svtplay-dl,leakim/svtplay-dl,OakNinja/svtplay-dl,OakNinja/svtplay-dl,dalgr/svtplay-dl,leakim/svtplay-dl,olof/svtplay-dl,qnorsten/svtplay-dl,qnorsten/svtplay-dl,leakim/svtplay-dl