fix a warning

implicit declaration of function ‘perror’

events.c

@@ -22,6 +22,7 @@
 #include "events.h"
 #include <assert.h>
 #include <stdlib.h>
+#include <stdio.h>
 
 t_events eventsInit(int initSize)
 {

rich_text.c

@@ -19,6 +19,7 @@
 #include "rich_text.h"
 #include <string.h>
 #include <stdlib.h>
+#include <stdio.h>
 
 
 char *strnstr(const char *s, const char *find, size_t slen)

time.c

@@ -19,6 +19,7 @@
 #include "time.h"
 #include <errno.h>
 #include <stdlib.h>
+#include <stdio.h>
 
 void normalize(struct timespec *t)
 {