stats: Functions with no arguments should specify(void)

... otherwise callers might pass arbitrary arguments without raising
a compiler error or warning.

Change-Id: Ia2de1d13df5f00dcc42493090734a635029d76b5
diff --git a/include/osmocom/core/stats.h b/include/osmocom/core/stats.h
index 6544dfa..a034a61 100644
--- a/include/osmocom/core/stats.h
+++ b/include/osmocom/core/stats.h
@@ -108,7 +108,7 @@
 extern struct osmo_stats_config *osmo_stats_config;
 
 void osmo_stats_init(void *ctx);
-int osmo_stats_report();
+int osmo_stats_report(void);
 
 int osmo_stats_set_interval(int interval);
 
diff --git a/src/stats.c b/src/stats.c
index 4267284..7b25ab1 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -175,7 +175,7 @@
 	return 0;
 }
 
-static int start_timer()
+static int start_timer(void)
 {
 	int rc;
 	int interval = osmo_stats_config->interval;
@@ -758,7 +758,7 @@
 
 /*** main reporting function ***/
 
-static void flush_all_reporters()
+static void flush_all_reporters(void)
 {
 	struct osmo_stats_reporter *srep;
 
@@ -781,7 +781,7 @@
 	}
 }
 
-int osmo_stats_report()
+int osmo_stats_report(void)
 {
 	/* per group actions */
 	TRACE(LIBOSMOCORE_STATS_START());