Fix "implicit declaration of function"

src/actions.c

@@ -45,6 +45,7 @@
 #include "winspector.h"
 #include "workspace.h"
 #include "xinerama.h"
+#include "usermenu.h"
 
 /****** Global Variables ******/
 

src/usermenu.c

@@ -74,6 +74,7 @@
 #include "actions.h"
 #include "funcs.h"
 #include "keybind.h"
+#include "xmodifier.h"
 
 #include "framewin.h"