Don't warn on by-name keys

.. which is apparently what the type of bare vals in *.sbt files are.

Fixes #3299, again.

main-settings/src/main/scala/sbt/std/TaskLinterDSL.scala

@@ -65,7 +65,7 @@ abstract class BaseTaskLinterDSL extends LinterDSL {
             val wrapperName = nme.decodedName.toString
             val (qualName, isSettingKey) =
               Option(qual.symbol)
-                .map(sym => (sym.name.decodedName.toString, sym.info <:< typeOf[SettingKey[_]]))
+                .map(sym => (sym.name.decodedName.toString, qual.tpe <:< typeOf[SettingKey[_]]))
                 .getOrElse((ap.pos.lineContent, false))
 
             if (!isSettingKey && !shouldIgnore && isTask(wrapperName, tpe.tpe, qual)) {

main-settings/src/test/scala/sbt/std/TaskPosSpec.scala

@@ -151,6 +151,15 @@ class TaskPosSpec {
     }
   }
 
+  locally {
+    import sbt._, Def._
+    def withKey(foo: => SettingKey[String]) = {
+      Def.task { if (true) foo.value }
+    }
+    val foo = settingKey[String]("")
+    withKey(foo)
+  }
+
   locally {
     import sbt._
     import sbt.Def._
@@ -171,4 +180,17 @@ class TaskPosSpec {
       (1 to 10).map(_ => foo.value)
     }
   }
+
+  locally {
+    import sbt._, Def._
+    def withKey(bar: => SettingKey[Int]) = {
+      Def.task {
+        List(42).map { _ =>
+          if (true) bar.value
+        }
+      }
+    }
+    val bar = settingKey[Int]("bar")
+    withKey(bar)
+  }
 }