Hey there,
I've been struggling with building LibreELEC.
Version: 8.2.5 (Commit 0beeae9)
Build within Docker Container: Ubuntu 16.04 (previous Ubuntu 18.04, but got more errors)
Compile target: PROJECT=RPi2 ARCH=arm
Build Log: Link
There was a similar problem here a year ago, but the solution won't help, because I'm already compiling as non-root.
I've been using Google before, but this missing gcc problem seems to be too specific.
I hope someone here can help me Thanks