Bug#1050350: flycheck: keep flycheck out of testing until it finds an uploader

[Manphiz <manphiz@gmail.com>]

control: merge 1050404 -1
control: block -1 by 1050459
control: tags -1 patch

Hi,

I've prepared an MR[1] to handle this, which requires a newer
emacs-buttercup which is being prepared at [2].  PTAL.

[1] https://salsa.debian.org/emacsen-team/flycheck/-/merge_requests/3
[2] https://salsa.debian.org/emacsen-team/emacs-buttercup/-/merge_requests/1

-- 
Manphiz