[IRGen][Test] Update tests for non-Linux platform support.

Tweak the tests slightly for WASM, Windows and Darwin.

rdar://23335318

Author: al45tair

test/IRGen/autorelease.sil

@@ -1,5 +1,7 @@
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) %s -enable-objc-interop -emit-ir | %FileCheck -check-prefix CHECK -check-prefix CHECK-%target-ptrsize -check-prefix %target-cpu -DINT=i%target-ptrsize %s
 
+// REQUIRE: objc_codegen
+
 // rdar://16565958
 
 import Builtin

test/IRGen/cf_objc_retainAutoreleasedReturnValue.swift

@@ -1,5 +1,9 @@
 // RUN: %target-swift-frontend -module-name cf_objc_retainAutoreleasedReturnValue -I %S/Inputs %s -enable-objc-interop -emit-ir | %FileCheck %s
-// RUN: %target-swift-frontend -module-name cf_objc_retainAutoreleasedReturnValue -I %S/Inputs %s -emit-ir | %FileCheck %s --check-prefix=NO_INTEROP
+
+// We need to require objc_codegen to avoid this test on WASM.
+// (That's why the other half of this test is in a separate file.)
+
+// REQUIRES: objc_codegen
 
 import CFBridgedType
 
@@ -10,15 +14,7 @@ public func foo() {
 
 // With interop enabled, this should use objc_retainAutoreleasedReturnValue()
 
-// CHECK-LABEL: define protected swiftcc void @"$s37cf_objc_retainAutoreleasedReturnValue3fooyyF"()
+// CHECK-LABEL: define {{.*}}swiftcc void @"$s37cf_objc_retainAutoreleasedReturnValue3fooyyF"()
 // CHECK: entry:
 // CHECK:   %0 = call {{.*}}@returnsACFBridgedType()
 // CHECK:   %1 = notail call ptr @llvm.objc.retainAutoreleasedReturnValue(ptr %0)
-
-// Without interop, it should call swift_retain() instead.
-
-// NO_INTEROP-LABEL: define protected swiftcc void @"$s37cf_objc_retainAutoreleasedReturnValue3fooyyF"()
-// NO_INTEROP: entry:
-// NO_INTEROP:   %0 = call {{.*}}@returnsACFBridgedType()
-// NO_INTEROP:   %1 = call ptr @swift_retain(ptr returned %0)
-