Fix VarArgs test for architectures without Float80

Since FileCheck does not know anything about the `#if` blocks in the
code, it tries to match the expected string against the output that is
simply never produced.

Solving this by giving it an expected string even on the architectures
that don't provide Float80.

Fixes <rdar://problem/45654446>

Author: moiseev

test/stdlib/VarArgs.swift

@@ -1,6 +1,6 @@
 // RUN: %target-run-stdlib-swift -parse-stdlib %s | %FileCheck %s
 // REQUIRES: executable_test
-// REQUIRES: rdar45654446
+
 import Swift
 
 #if _runtime(_ObjC)
@@ -117,26 +117,30 @@ func test_varArgs5() {
   }
 
   // CHECK: rdar-32547102: 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0
-  withVaList(args) {
+  _ = withVaList(args) {
     vprintf(format + "\n", $0)
   }
 }
 test_varArgs5()
 
-#if !os(Windows) && (arch(i386) || arch(x86_64))
 func test_varArgs6() {
   // Verify alignment of va_list contents when `Float80` is present.
   let  i8 = Int8(1)
   let f32 = Float(1.1)
   let f64 = Double(2.2)
+#if !os(Windows) && (arch(i386) || arch(x86_64))
   let f80 = Float80(4.5)
   my_printf("a %g %d %g %d %Lg %d %g a\n",            f32, i8, f64, i8, f80, i8, f32)
   my_printf("b %d %g %d %g %d %Lg %d %g b\n",     i8, f32, i8, f64, i8, f80, i8, f32)
+#else // just a dummy to make FileCheck happy, since it ignores `#if`s
+  let dummy = Double(4.5)
+  my_printf("a %g %d %g %d %g %d %g a\n",            f32, i8, f64, i8, dummy, i8, f32)
+  my_printf("b %d %g %d %g %d %g %d %g b\n",     i8, f32, i8, f64, i8, dummy, i8, f32)
+#endif
   // CHECK: a 1.1 1 2.2 1 4.5 1 1.1 a
   // CHECK: b 1 1.1 1 2.2 1 4.5 1 1.1 b
 }
 test_varArgs6()
-#endif
 
 
 // CHECK: done.