qbs files: Compile everything with QT_NO_CAST_TO_ASCII

It appears in qtcreator.pri

Change-Id: Iea74d4d06146f94fd1022eaae3074da88d6e22f3
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

qbs/defaults.js

@@ -7,7 +7,8 @@ function defines(qbs)
 {
     var list = [
         'IDE_LIBRARY_BASENAME="lib"',
-        "QT_DISABLE_DEPRECATED_BEFORE=0x040900"
+        "QT_DISABLE_DEPRECATED_BEFORE=0x040900",
+        "QT_NO_CAST_TO_ASCII"
     ]
     if (testsEnabled(qbs))
         list.push("WITH_TESTS")