KVM selftests fixes for 6.8 merge window:
- Fix an annoying goof where the NX hugepage test prints out garbage
instead of the magic token needed to run the text.
- Fix build errors when a header is delete/moved due to a missing flag
in the Makefile.
- Detect if KVM bugged/killed a selftest's VM and print out a helpful
message instead of complaining that a random ioctl() failed.
- Annotate the guest printf/assert helpers with __printf(), and fix the
various bugs that were lurking due to lack of said annotation.
A small subset of these was included in 6.7-rc as well.