deal with %PATH% containing parentheses

we need to make cmd escape the expanded output, so it doesn't confuse
its own command line parsing (which happens later!).

Change-Id: I0c2c71d276c0aebe3c2163f7f08db8050a14d7ce
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

mkspecs/features/qt_functions.prf

@@ -157,7 +157,8 @@ defineTest(qtPrepareTool) {
                 error("Operating system not supported.")
             $$1 = "$$var=$$join(deppath, :)${$$var:+:\$$$var} $$eval($$1)"
         } else {
-            $$1 = "(set PATH=$$join(deppath, ;);%PATH%) & $$eval($$1)"
+            # Escape closing parens when expanding %PATH%, otherwise cmd confuses itself.
+            $$1 = "(set PATH=$$join(deppath, ;);%PATH:)=^)%) & $$eval($$1)"
         }
     }