DolphinWX: Add a progress dialog host command

Allows feedback from backends to be communicated to the user when
long-running operation are performed (e.g. shader compilation).

Source/Core/DolphinNoGUI/MainNoGUI.cpp

@@ -136,6 +136,10 @@ void Host_YieldToUI()
 {
 }
 
+void Host_UpdateProgressDialog(const char* caption, int position, int total)
+{
+}
+
 #if HAVE_X11
 #include <X11/Xlib.h>
 #include <X11/keysym.h>