SI-8263 Avoid SOE in Symbol#logicallyEnclosingMember under Scala 2.11

Since the fix for SI-2066, Scala 2.11 calls logicallyEnclosingMember on the
`x` in the expansion of the task macro:

    InitializeInstance.app[[T0[x]](T0[java.io.File], T0[java.io.File]), Seq[java.io.File]]

This exposed the fact that SBT has created `T0` with `NoSymbol` as
the owner. This led to the a SOE.

I will also change the compiler to be more tolerant of this, but we
can observe good discipline in the macro and pick a sensible owner.

util/appmacro/src/main/scala/sbt/appmacro/KListBuilder.scala

@@ -24,7 +24,7 @@ object KListBuilder extends TupleBuilder
 		val kconsTC: Type = kconsTpe.typeConstructor
 
 		/** This is the L in the type function [L[x]] ...  */
-		val tcVariable: TypeSymbol = newTCVariable(NoSymbol)
+		val tcVariable: TypeSymbol = newTCVariable(util.initialOwner)
 
 		/** Instantiates KCons[h, t <: KList[L], L], where L is the type constructor variable */
 		def kconsType(h: Type, t: Type): Type =
@@ -65,4 +65,4 @@ object KListBuilder extends TupleBuilder
 		val alistInstance: ctx.universe.Tree = TypeApply(select(Ident(alist), "klist"), TypeTree(representationC) :: Nil)
 		def extract(param: ValDef) = bindKList(param, Nil, inputs.map(_.local))
 	}
-}
+}

util/appmacro/src/main/scala/sbt/appmacro/TupleNBuilder.scala

@@ -25,7 +25,7 @@ object TupleNBuilder extends TupleBuilder
 
 		val ctx: c.type = c
 		val representationC: PolyType = {
-			val tcVariable: Symbol = newTCVariable(NoSymbol)
+			val tcVariable: Symbol = newTCVariable(util.initialOwner)
 			val tupleTypeArgs = inputs.map(in => typeRef(NoPrefix, tcVariable, in.tpe :: Nil).asInstanceOf[global.Type])
 			val tuple = global.definitions.tupleType(tupleTypeArgs)
 			PolyType(tcVariable :: Nil, tuple.asInstanceOf[Type] )