linux/compiler-gcc6.h missing when compiling for VIM2 on Nougat branch

[Road-Drum]

when running make CROSS_COMPILE=aarch64-linux-gnu- for kvim2 in Nougat branch, I got the error linux/compiler-gcc6.h not found or missing even with correct toolchains installed by following this guide.

Manually checking$uboot\include\linux in Nougat branch reveals that only up to compiler-gcc5.h was included. Naturally the temporary solution is to get gcc-5 linaro and gnu-rm toolchains,

Is the guide for installing toolchains for VIM2 was incorrect? Or compiler-gcc6.h actually exist on different branch? As VIM2 only has Nougat branch as per documentation, I presume this is the only branch that I can work on to build uboot and android for VIM2.