Bug#1017730: pmix: drop Build-Depends: pandoc

[Drew Parsons]

Source: pmix
Version: 4.2.0+really.4.1.2-2
Followup-For: Bug #1017730

Hi Alistair, would be useful if the pandoc removal patch could be
applied to the 4.2.0+really.4.1.2 versions.

Cheers,
Drew