[RFC] raise gcc/make versions for 20.x

[Paul Spooren]

Hi,

I've seen two patches for version raises of build requirements and 
would like to know if we should merge them before or after 20.x.

make: 3.81.x -> 4.1.x
gcc: 4.8 -> 6.x

I'm in favor to merge both *before* the branch.

Best,
Paul