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@11065 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mac/uma.cpp

@@ -3,7 +3,7 @@
 #include "wx/mac/uma.h"
 #include "wx/mac/aga.h"
 
-#ifndef __UNIX__
+#ifndef __DARWIN__
   #include <Navigation.h>
 #endif
 
@@ -84,7 +84,7 @@ void UMAInitToolbox( UInt16 inMoreMastersCalls )
 #endif // UMA_USE_WINDOWMGR
 #endif
 		
-#ifndef __UNIX__
+#ifndef __DARWIN__
 #if TARGET_CARBON
 // Call currently implicitely done :		InitFloatingWindows() ;
 #else