TuxMake temporarily disabled RISC-V support with clang-nightly because
apt.llvm.org currently does not have LLVM 19 builds for the unstable
distribution, which the RISC-V container uses as a base.
While this issue gets sorted, drop RISC-V builds with clang-nightly, as
that combination will error now.
Link: https://lore.kernel.org/20240131174445.GA535345@dev-arch.thelio-3990X/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Signed-off-by: Nathan Chancellor <nathan@kernel.org>