fix command over-escaping in vcproj files

the vs ide executes the commands verbatim, so they must not be
make-escaped.

Task-number: QTBUG-31289
Change-Id: Ie73fd5c4da5527c2d10bc94ccdf60f8a1ca21351
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

mkspecs/features/qt_functions.prf

@@ -224,8 +224,10 @@ defineTest(qtAddToolEnv) {
                 else: infix =
                 val = "(set $$name=$$join(value, ;)$$infix) &"
             }
-            contains(MAKEFILE_GENERATOR, MS.*): val ~= s,%,%%,g
-            else: val ~= s,\\\$,\$\$,g
+            !contains(TEMPLATE, vc.*) {
+                contains(MAKEFILE_GENERATOR, MS.*): val ~= s,%,%%,g
+                else: val ~= s,\\\$,\$\$,g
+            }
             $$1 = "$$val $$eval($$1)"
         }
     }