adding conditionals for NSString bridges

src/osx/core/cfstring.cpp

@@ -693,6 +693,8 @@ wxString wxCFStringRef::AsString(wxFontEncoding encoding) const
     return AsString( get(), encoding );
 }
 
+#ifdef __WXMAC__
+
 wxString wxCFStringRef::AsString( NSString* ref, wxFontEncoding encoding )
 {
     return AsString( (CFStringRef) ref, encoding );
@@ -703,6 +705,8 @@ wxString wxCFStringRef::AsStringWithNormalizationFormC( NSString* ref, wxFontEnc
     return AsStringWithNormalizationFormC( (CFStringRef) ref, encoding );
 }
 
+#endif
+
 //
 // wxMacUniCharBuffer
 //