[PATCH 2/2] treewide: Simplify setenv() calls

[Daniel Brát]

Since this patch, I am getting a bunch of
'warning: format not a string literal and no format arguments [-Wformat-security]'
warnings when compiling for aarch64 rpi. I am using 'aarch64-linux-gnu-gcc 7.5.0'
on Ubuntu 18.04. Full compmpile log: https://pastebin.com/iCsBJbXU