Introduce SourceManager::PredefinesFileID, to allow each checking of whether
a source location came from the predefines buffer.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174190 91177308-0d34-0410-b5e6-96231b3b80d8
For ModuleLoader::makeModuleVisible() also pass the source location where the
module import occurred.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174191 91177308-0d34-0410-b5e6-96231b3b80d8
[modules] Introduce ModuleFile::DirectImportLoc which is the source location
where the module was explicitly or implicitly imported in the local translation unit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174192 91177308-0d34-0410-b5e6-96231b3b80d8
libclang: add comments for CXStringFlag


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174194 91177308-0d34-0410-b5e6-96231b3b80d8
libclang: document the purpose of createNull()


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174195 91177308-0d34-0410-b5e6-96231b3b80d8