Add clang_Location_isFromMainFile() to libclang.

Also bump the minor version number and update libclang.exports.

Reviewed by: Dmitri Gribenko, Doug Gregor

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187994 91177308-0d34-0410-b5e6-96231b3b80d8