Do not replace compiler-gcc.h. This is necessary now, as we are
replacing compiler-gcc.h by default again, as it is needed for most
kernels. Not increasing the pkgrel to avoid unnecessary rebuild, I have
verified that this works.
NOTE: in the last commit message, I wrote about OVERWRITE_GCC=0. But
the variable is called REPLACE_GCC, as I've decided to rename it before
submitting. I forgot to change it in the commit message.
[skip ci]: this kernel takes more than one hour to build, so it won't
finish in CI.
