Cleanup X86 IOAPIC code from interrupt remapping details These patches move all interrupt remapping specific checks out of the x86 core code and replaces the respective call-sites with function pointers. As a result the interrupt remapping code is better abstraced from x86 core interrupt handling code. The code was rebased to v3.8-rc4 and tested on systems with AMD-Vi and Intel VT-d (both capable of interrupt remapping). The systems were tested with IOMMU enabled and with IOMMU disabled. No issues were found.