Detect source location overflow due includes

Summary:
As discussed in http://lists.llvm.org/pipermail/cfe-dev/2019-October/063459.html
the overflow of the souce locations (limited to 2^31 chars) can generate all sorts of
weird things (bogus warnings, hangs, crashes, miscompilation and correct compilation).
In debug mode this assert would fail. So it might be a good start, as in PR42301,
to detect the failure and exit with a proper error message.

Reviewers: rsmith, thakis, miyuki

Reviewed By: miyuki

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70183