modified configure to allow configuration of wxMotif under Darwin/Mac OS X

wxWindows can be configured as wxMac or wxMotif under Mac OS X
replaced __WXMAC_X__ define by __DARWIN__ (general Darwin related issues)
moved dlopen/dlerror code to dynlib.cpp to make it available for wxMotif


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@11061 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/app.h

@@ -65,6 +65,9 @@ public:
 
     // the virtual functions which may/must be overridden in the derived class
     // -----------------------------------------------------------------------
+#ifdef __DARWIN__
+    virtual ~wxAppBase() { }
+#endif
 
         // called during the program initialization, returning FALSE from here
         // prevents the program from continuing - it's a good place to create
@@ -315,11 +318,6 @@ protected:
     // does any of our windows has focus?
     bool m_isActive;
 #endif // wxUSE_GUI
-
-#ifdef __WXMAC_X__
-public:
-    virtual ~wxAppBase() {}  // Added min for Mac X
-#endif
 };
 
 // ----------------------------------------------------------------------------