Fix scala#4773: Add regression test

Author: nicolasstucki

tests/pos/i4773.scala

@@ -0,0 +1,6 @@
+import scala.quoted._
+object Foo {
+  inline def foo2(): Unit = ~foo2Impl()
+  def foo2Impl(): Expr[Unit] = '()
+  inline def foo(): Unit = foo2()
+}