db_flatstore: update timestamp for kamailio specific rpc rotate

- do also in 'rotate' command, not only in 'k_rotate'
- from a patch by Abdelkader Allam

modules/db_flatstore/flat_rpc.c

@@ -32,6 +32,7 @@
 
 #include "flat_rpc.h"
 #include "flatstore_mod.h"
+#include "km_flatstore_mod.h"
 
 #include <time.h>
 
@@ -43,6 +44,7 @@
  */
 static void rotate(rpc_t* rpc, void* c)
 {
+	*km_flat_rotate = time(0);
 	*flat_rotate = time(0);
 }