[SystemZ] Add header files to Makefile / module.modulemap

This should fix build-bot failures after r233804.

The patch also adds a "systemz" feature, and renames the
"transactional-execution" feature to "htm", since it turns
out "-" is not a legal character in module feature names.

llvm-svn: 233807
diff --git a/clang/lib/Headers/module.modulemap b/clang/lib/Headers/module.modulemap
index 062464e..bb2ca95 100644
--- a/clang/lib/Headers/module.modulemap
+++ b/clang/lib/Headers/module.modulemap
@@ -169,6 +169,19 @@
       header "__wmmintrin_pclmul.h"
     }
   }
+
+  explicit module systemz {
+    requires systemz
+    export *
+
+    header "s390intrin.h"
+
+    explicit module htm {
+      requires htm
+      header "htmintrin.h"
+      header "htmxlintrin.h"
+    }
+  }
 }
 
 module _Builtin_stddef_max_align_t [system] [extern_c] {