Fix dozens of compiler warnings across the board

Change-Id: I166109dc05d3323b92cd2a42f0c7e6009950e15d
diff --git a/src/pcu_vty.c b/src/pcu_vty.c
index 535d512..3b5996c 100644
--- a/src/pcu_vty.c
+++ b/src/pcu_vty.c
@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 #include <osmocom/vty/logging.h>
 #include <osmocom/vty/stats.h>
 #include <osmocom/vty/misc.h>