Fix Qbs build

Amends f84199f8b7 and
reverts 796cfceb3a.

Change-Id: I7eb686c012bd99cddf36aa16219e3f33de2b15b2
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/utils.qbs

@@ -471,6 +471,7 @@ Project {
 
         Export {
             Depends { name: "Qt"; submodules: ["concurrent", "widgets" ] }
+            Depends { name: "Tasking" }
             cpp.includePaths: base.concat("mimetypes2")
         }
     }

tests/auto/solutions/tasking/tasking.qbs

@@ -1,7 +1,6 @@
 QtcAutotest {
     name: "Tasking autotest"
 
-    Depends { name: "Tasking" }
     Depends { name: "Utils" }
 
     files: "tst_tasking.cpp"

tests/auto/utils/async/async.qbs

@@ -2,7 +2,6 @@ import qbs
 
 QtcAutotest {
     name: "Async autotest"
-    Depends { name: "Tasking" }
     Depends { name: "Utils" }
     files: "tst_async.cpp"
 }

tests/manual/tasktree/tasktree.qbs

@@ -4,7 +4,6 @@ QtcManualtest {
     name: "Manual TaskTree test"
     type: ["application"]
 
-    Depends { name: "Tasking" }
     Depends { name: "Utils" }
 
     files: [