Bring in sephe's recent intr/apic work to x86_64.
The following commits:
6ab7c3a intr: Clean up comment of Local APIC TPR
84bf7d5 intr: Remove unused TRP macros
e4a4c49 intr: Remove unused typedef
507bf37 intr: Make sure that changing IPI offset will also update related TPR
072d9b3 intr: Move IO/APIC IDT vector offset into isa/intr_machdep.h
7b32a0a apic: Remove unused macros and duplicated comment
2ce3ae8 apic: Remove unused macros
26408d7 intr: Remove call_fast_unpend() declaration
87e3ca2 intr: Start hardware interrupt at IDT_OFFSET
90a567f apic: Clear all entries in int table