x86/kgdb: Replace bool_int_array[NR_CPUS] with bitmap

Straigntforward conversion from:

    int was_in_debug_nmi[NR_CPUS]

to:

    DECLARE_BITMAP(was_in_debug_nmi, NR_CPUS)

Saves about 2 kbytes in BSS for NR_CPUS=512.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1443271638-2568-1-git-send-email-dvlasenk@redhat.com


[ Tidied up the code a bit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>