To build the kernel, we need to have gcc.
Using the host gcc isn't going to work with the path interposer given the comments that are in the configuration file: The gcc binary contains code that drives the compilation. It then runs other binaries like cc1. Passing -B to GCC can make it find cc1 but (1) that's ultra dirty, and (2) it fails to find it plugins.
As GCC was removed from the prebuilts in AOSP, and that depending on binaries isn't great, the idea would be to build GCC ourselves.
Since we were already doing it in Replicant 6, we could probably reuse the script Wolfgang did and adapt it to build a arm-none-eabi toolchain to build only the kenrel (to avoid dependencies on the headers needed for androideabi, which are now gone in the branches/tags of AOSP used by Replicant 11).
So far we need these additional dependencies on Trisquel 8:
apt install libgmp-dev libmpfr-dev libmpc-dev