Revert r167801, "[preprocessor] When #including something that contributes no
tokens at all,". This change broke External/Nurbs in LLVM test-suite.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@167858 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed