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/carbon/bitmap.cpp

@@ -29,7 +29,7 @@ IMPLEMENT_ABSTRACT_CLASS(wxBitmapBase , wxGDIObject )
 IMPLEMENT_ABSTRACT_CLASS(wxBitmapHandlerBase, wxObject ) 
 #endif
 
-#ifdef __UNIX__
+#ifdef __DARWIN__
     #include <ApplicationServices/ApplicationServices.h>
 #else
     #include <PictUtils.h>
@@ -841,7 +841,7 @@ PicHandle wxBitmap::GetPict() const
 
    if( mask )
    {
-#ifdef __UNIX__
+#ifdef __DARWIN__
        RGBColor trans = white;
 #else
        RGBBackColor( &gray );