Touch up tests for new <version> header; fix module.modulemap.

This patch does some housekeeping for the new <version> header.
It adds it to the module.modulemap, and the double_include.sh.cpp test.

Additionally it corrects the // UNSUPPORTED options for the libc++
specific test. The header needs to compile under C++03 to support
modules, and it should compile under all available compilers.

llvm-svn: 329144
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: acc32abb117809fecd82074219f97a1258f771e0
diff --git a/include/module.modulemap b/include/module.modulemap
index 076ef23..cf92fa0 100644
--- a/include/module.modulemap
+++ b/include/module.modulemap
@@ -470,6 +470,10 @@
     export initializer_list
     export *
   }
+  module version {
+    header "version"
+    export *
+  }
 
   // FIXME: These should be private.
   module __bit_reference { header "__bit_reference" export * }