Fixup the CRT api test

Author: hyp

test/stdlib/CRT.swift

@@ -0,0 +1,12 @@
+// RUN: %target-typecheck-verify-swift
+// REQUIRES: OS=windows-msvc
+
+// This file has CRT-specific C stdlib tests, that use
+// some APIs present only in CRT.
+
+import CRT
+
+func complexFunctionsAvailableInSwift() {
+  let complexValue = _Cbuild(1.0, 2.0) // Construct a complex double using MSVC-specific API.
+  let _ = creal(complexValue)
+}