The error variable breaks build on CentOS 6.7, due to a collision with a
global error symbol:

    CC       util/parse-events.o
  cc1: warnings being treated as errors
  util/parse-events.c:419: error: declaration of ‘error’ shadows a global
  declaration
  util/util.h:135: error: shadowed declaration is here
  util/parse-events.c: In function ‘add_tracepoint_multi_event’:
  ...

Using different argument names instead to fix it.
Reported-by: Vinson Lee <vlee@twopensource.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: linux-tip-commits@vger.kernel.org
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Raphael Beamonte <raphael.beamonte@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150929150531.GI27383@krava.redhat.com
[ Fix one more case, at line 770 ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>