perf record: Add new -I option to sample interrupted machine state

Add -I/--intr-regs option to capture machine state registers at
interrupt.

Add the corresponding man page description

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1411559322-16548-6-git-send-email-eranian@google.com
Cc: cebbert.lkml@gmail.com
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>