core: fix typo added with pkg stats

- reported by Juha Heinanen

mem/f_malloc.c

@@ -56,7 +56,7 @@
 #include "../bit_scan.h"
 #include "../cfg/cfg.h" /* memlog */
 #ifdef MALLOC_STATS
-#include "../evnets.h"
+#include "../events.h"
 #endif