When fixing this module to build on PC98, I actually broke the build on
ARM64. On PC98 we need to pull in the sources from the MACHINE_CPUARCH
(i386), but on ARM64 we need to use the MACHINE, as MACHINE_CPUARCH is
set to aarch64 instead of just arm64.
Where the cloudabi64 kernel can be used to execute 64-bit CloudABI
binaries, this one should be used for 32-bit binaries. Right now it
works on i386 and amd64.