LibGfx: Fix debug-printing colors

The operator has to live in the namespace Gfx.

Libraries/LibGfx/Color.cpp

@@ -432,12 +432,12 @@ Optional<Color> Color::from_string(const StringView& string)
 
     return Color(r.value(), g.value(), b.value(), a.value());
 }
-}
 
 const LogStream& operator<<(const LogStream& stream, Color value)
 {
     return stream << value.to_string();
 }
+}
 
 bool IPC::encode(IPC::Encoder& encoder, const Color& color)
 {