Support building with -Werror=strict-prototypes / -Werror=old-style-definition

Unfortunately "-std=c99" is not sufficient to make gcc ignore code that
uses constructs of earlier C standards, which were abandoned in C99.

See https://lwn.net/ml/fedora-devel/Y1kvF35WozzGBpc8@redhat.com/ for
some related discussion.

Change-Id: I84fd99442d0cc400fa562fa33623c142649230e2
diff --git a/src/vty/cpu_sched_vty.c b/src/vty/cpu_sched_vty.c
index dbb3cd5..301e7a6 100644
--- a/src/vty/cpu_sched_vty.c
+++ b/src/vty/cpu_sched_vty.c
@@ -89,7 +89,7 @@
 };
 
 /* returns number of configured CPUs in the system, or negative otherwise */
-static int get_num_cpus() {
+static int get_num_cpus(void) {
 	static unsigned int num_cpus = 0;
 	long ln;
 
diff --git a/src/vty/logging_vty.c b/src/vty/logging_vty.c
index c83dafd..59c8a9c 100644
--- a/src/vty/logging_vty.c
+++ b/src/vty/logging_vty.c
@@ -1196,7 +1196,7 @@
 
 /*! Register logging related commands to the VTY. Call this once from
  *  your application if you want to support those commands. */
-void logging_vty_add_cmds()
+void logging_vty_add_cmds(void)
 {
 	install_lib_element_ve(&enable_logging_cmd);
 	install_lib_element_ve(&disable_logging_cmd);
diff --git a/src/vty/stats_vty.c b/src/vty/stats_vty.c
index e5acfa2..299ec24 100644
--- a/src/vty/stats_vty.c
+++ b/src/vty/stats_vty.c
@@ -742,7 +742,7 @@
  *  Call this once during your application initialization if you would
  *  like to have stats VTY commands enabled.
  */
-void osmo_stats_vty_add_cmds()
+void osmo_stats_vty_add_cmds(void)
 {
 	install_lib_element_ve(&show_stats_cmd);
 	install_lib_element_ve(&show_stats_level_cmd);