Optimize tree page table implementation
Optimize tree page table implementation

This commit adds the cached virtual context page table into the
hypervisor's context. The virtual context root page table will be
dereferenced only if a new page has been mapped.

This approach speeds up the execution of `make all` from approx. 37min
to 15min. Compared to the current master HEAD, this is a slight increase
of execution time of approx. 50secs.

ChristianMoesl/selfie,ChristianMoesl/selfie,cksystemsteaching/selfie,cksystemsteaching/selfie,cksystemsteaching/selfie