[PATCH] build/prereq: merge ifndef IB block together

[Sven Roederer]

Am Donnerstag, 31. Dezember 2020, 20:35:47 CET schrieb Paul Spooren:
> 
> Merged and backported.
> 

I think 4f3806364011aa3aef26fcab2e7b71837a777bcc needs to be backported too, 
to make it work.

Sven