Introduce the notion of excluded headers into the module map
description. Previously, one could emulate this behavior by placing
the header in an always-unavailable submodule, but Argyrios guilted me
into expressing this idea properly.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165921 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed