tests: remove uses of println() that are not relevant to the tests

Swift SVN r28016

test/DebugInfo/alloca-init.swift

@@ -1,5 +1,7 @@
 // RUN: %target-swift-frontend %s -emit-ir -g -o - | FileCheck %s
 
+func markUsed<T>(t: T) {}
+
 class A {
   var a : A?
   // CHECK: define {{.*}}1AcfMS0_FT_S0_
@@ -8,7 +10,7 @@ class A {
     // CHECK:   store {{.*}} %0, {{.*}}, align
     // CHECK-NOT: !dbg
     // CHECK: call {{.*}}llvm.dbg.declare
-    println("Hi")
+    markUsed("Hi")
   }
 }