Add wxwidgets patch for unicode pasteboard.

Based on upstream https://github.com/wxWidgets/wxWidgets/commit/
73fca4c37d1ee2e9e495aaa68442cdfcb4243b52

Fixes: lp:1559103

patches/wxwidgets-3.0.2_macosx_unicode_pasteboard.patch

@@ -0,0 +1,16 @@
+--- src/osx/carbon/dataobj.cpp	2016-09-17 10:26:10.000000000 +1200
++++ src/osx/carbon/dataobj.cpp	2016-09-17 10:26:23.000000000 +1200
+@@ -458,13 +458,11 @@ bool wxDataObject::GetFromPasteboard( vo
+                                 pastelocationset = true;
+                            }
+                         }
+-#if 0 // See https://groups.google.com/forum/#!topic/wx-dev/wFxevpvbhvQ/discussion
+                         else if ( flavorFormat.GetType() != wxDF_PRIVATE )
+                         {
+                             // indicate the expected format for the type, benefiting from native conversions eg utf8 -> utf16
+                             flavorType = (CFStringRef) wxDataFormat( flavorFormat.GetType()).GetFormatId();
+                         }
+-#endif
+ 
+                         err = PasteboardCopyItemFlavorData( pasteboard, itemID, flavorType , &flavorData );
+                         if ( err == noErr )