It is not good taste to have macros with additions that do not have
parenthesises around them.  This patch parethesizes the IRQ vector
macros for x86_64 arch.

Note, this caused me a bit of heart-ache debugging lguest64.

[ tglx: arch/x86 adaptation ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>