Previously we enabled the timer interrupt, before the kernel was notified of our time increment, so when a clock interrupt happened, it would increment the tick count, but add 0 to the system time, resulting in an invalid state, in which timers would be inserted into the wrong timer table slot. Fixes CORE-16253
* Fix some broken code
* Add some ASSERTs
* Use ApicWriteIORedirectionEntry where appropriate
* Use KeQueryInterruptHandler/KeRegisterInterruptHandler to save/restore the old handler instead of saving the KIDTENTRY
* Move HalpProfileInterruptHandler to apictimer.c and implement it
* Use READ/WRITE_REGISTER macros
* Add some symbolic names
Lazy IRQL feature has issues with interrupt delivery on VirtualBox, so disable it for now.
For the feature description, see commit d28eae967a
Meanwhile, merge and clean up APIC headers a bit