[Driver][Mips] Support mips64-linux-gnuabi64 / mips64el-linux-gnuabi64 target triples.

The patch fixes the bug #19869.
http://llvm.org/bugs/show_bug.cgi?id=19869

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211619 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify optimization-remark.c test following r211610

With LocTrackingOnly there's no longer a user-facing distinction so the NDEBUG
checks can go away. (Except maybe column info, but -verify only checks line
numbers anyway.)

Also add a RUN line to validate the traditional !LocTrackingOnly case.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211622 91177308-0d34-0410-b5e6-96231b3b80d8
Add directory_iterator for (non-recursive) iteration of VFS directories

The API is based on sys::fs::directory_iterator, but it allows iterating
over overlays and the yaml-based VFS.  For now, it isn't used by
anything (except its tests).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211623 91177308-0d34-0410-b5e6-96231b3b80d8
Use appropriate default PIE settings for OpenBSD.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211624 91177308-0d34-0410-b5e6-96231b3b80d8