Added PowerState casting operator to Variant

Without it Godot does not build with PTRCALL_ENABLED

core/variant.cpp

@@ -2178,6 +2178,11 @@ Variant::operator IP_Address() const {
 	return IP_Address( operator String() );
 }
 
+Variant::operator PowerState() const
+{
+	return (PowerState) operator int();
+}
+
 Variant::Variant(bool p_bool) {
 
 	type=BOOL;

core/variant.h

@@ -45,6 +45,7 @@
 #include "path_db.h"
 #include "simple_type.h"
 #include "os/input_event.h"
+#include "os/power.h"
 #include "color.h"
 #include "face3.h"
 #include "ref_ptr.h"
@@ -254,6 +255,7 @@ public:
 	operator Orientation() const;
 
 	operator IP_Address() const;
+	operator PowerState() const;
 
 
 	Variant(bool p_bool);