Fix Modules/{builtin-import.mm,umbrella-header-include-builtin.mm} to be able to handle non-Darwin targets

Summary: Also makes them pass on Darwin, if the default target triple is a Linux triple.

Reviewers: bruno, rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D38364

llvm-svn: 314524
diff --git a/clang/test/Modules/builtin-import.mm b/clang/test/Modules/builtin-import.mm
index 2536ac5..cbc312b 100644
--- a/clang/test/Modules/builtin-import.mm
+++ b/clang/test/Modules/builtin-import.mm
@@ -1,7 +1,5 @@
-// REQUIRES: system-darwin
-
 // RUN: rm -rf %t
-// RUN: %clang -cc1 -fsyntax-only -nostdinc++ -isysroot %S/Inputs/libc-libcxx/sysroot -isystem %S/Inputs/libc-libcxx/sysroot/usr/include/c++/v1 -std=c++11 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -x objective-c++ -fmodules-local-submodule-visibility %s
+// RUN: %clang -cc1 -fsyntax-only -nobuiltininc -nostdinc++ -isysroot %S/Inputs/libc-libcxx/sysroot -isystem %S/Inputs/libc-libcxx/sysroot/usr/include/c++/v1 -isystem %S/Inputs/libc-libcxx/sysroot/usr/include -std=c++11 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -x objective-c++ -fmodules-local-submodule-visibility %s
 
 #include <stdio.h>
 #include <stddef.h>