perf parse-events: Fix an old style declaration

Fixes: a26e471 (perf tools: Move ALLOC_LIST into a function)
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200609053610.206588-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.y

@@ -26,7 +26,7 @@ do { \
 		YYABORT; \
 } while (0)
 
-static struct list_head* alloc_list()
+static struct list_head* alloc_list(void)
 {
 	struct list_head *list;