perf evlist: Handle default value for 'pages' on mmap method

Every tool that calls this and allows the user to override the value
needs this logic.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.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-lwscxpg57xfzahz5dmdfp9uz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 07d56b3..17e9c80 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -79,7 +79,8 @@
 int perf_evlist__start_workload(struct perf_evlist *evlist);
 
 int perf_evlist__alloc_mmap(struct perf_evlist *evlist);
-int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite);
+int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
+		      bool overwrite);
 void perf_evlist__munmap(struct perf_evlist *evlist);
 
 void perf_evlist__disable(struct perf_evlist *evlist);