Rename lib/Headers/module.map to module.modulemap

Don't install a file using the legacy spelling.

llvm-svn: 206431
diff --git a/clang/docs/Modules.rst b/clang/docs/Modules.rst
index eec0b77..183a8f2 100644
--- a/clang/docs/Modules.rst
+++ b/clang/docs/Modules.rst
@@ -839,7 +839,7 @@
 =================================
 The Clang source code provides additional information about modules:
 
-``clang/lib/Headers/module.map``
+``clang/lib/Headers/module.modulemap``
   Module map for Clang's compiler-specific header files.
 
 ``clang/test/Modules/``