So that the index passed doesn't have to start at zero, being
decremented from an offset specified when declaring the strarray before
being used as the real array index.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-k1ce6uqyt4qar9edrj3mevod@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>