Add new pending test for sbt/sbt#1237

This test shows that macros that simply return their argument produce
a stack overflow during extraction of used names.

Consider a macro `foo(c: Context)(a: c.Expr[Any]) = a`. An
application of this macro such as `foo(someVal)` will lead to the
expansion `someVal`. sbt will extract the `original` tree from it,
and find `foo(someVal)`, and recurse infinitely on `someVal`.

sbt/src/sbt-test/source-dependencies/macro-arg-dep-stackoverflow/macro-client/Client.scala

@@ -0,0 +1,6 @@
+package macros
+
+object Client {
+  val a = 1
+  def test = Foo.bar(a)
+}

sbt/src/sbt-test/source-dependencies/macro-arg-dep-stackoverflow/macro-provider/Foo.scala

@@ -0,0 +1,9 @@
+package macros
+
+import scala.language.experimental.macros
+import scala.reflect.macros.Context
+
+object Foo {
+  def bar(a: Any): Any = macro impl
+  def impl(c: Context)(a: c.Expr[Any]): c.Expr[Any] = a
+}

sbt/src/sbt-test/source-dependencies/macro-arg-dep-stackoverflow/pending

@@ -0,0 +1,2 @@
+# We only want to make sure we can compile this without stack overflow
+> compile

sbt/src/sbt-test/source-dependencies/macro-arg-dep-stackoverflow/project/build.scala

@@ -0,0 +1,29 @@
+import sbt._
+import Keys._
+
+object build extends Build {
+	val defaultSettings = Seq(
+		libraryDependencies <+= scalaVersion("org.scala-lang" % "scala-reflect" % _ ),
+		incOptions := incOptions.value.withNameHashing(true)
+	)
+
+	lazy val root = Project(
+	   base = file("."),
+	   id = "macro",
+	   aggregate = Seq(macroProvider, macroClient),
+	   settings = Defaults.defaultSettings ++ defaultSettings
+	)
+
+	lazy val macroProvider = Project(
+	   base = file("macro-provider"),
+	   id = "macro-provider",
+	   settings = Defaults.defaultSettings ++ defaultSettings
+	)
+
+	lazy val macroClient = Project(
+	   base = file("macro-client"),
+	   id = "macro-client",
+	   dependencies = Seq(macroProvider),
+	   settings = Defaults.defaultSettings ++ defaultSettings
+	)
+}