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/mac/bitmap.h

@@ -101,8 +101,8 @@ class WXDLLEXPORT wxBitmapHandler: public wxBitmapHandlerBase
   DECLARE_DYNAMIC_CLASS(wxBitmapHandler)
 public:
   wxBitmapHandler() { m_name = ""; m_extension = ""; m_type = 0; };
-#ifdef __WXMAC_X__
-  virtual ~wxBitmapHandler() {}  // Added min for Mac X
+#ifdef __DARWIN__
+  virtual ~wxBitmapHandler() { }
 #endif
 
   virtual bool Create(wxBitmap *bitmap, void *data, long flags, int width, int height, int depth = 1);