DataFlowSanitizer; Clang changes.

DataFlowSanitizer is a generalised dynamic data flow analysis.

Unlike other Sanitizer tools, this tool is not designed to detect a
specific class of bugs on its own.  Instead, it provides a generic
dynamic data flow analysis framework to be used by clients to help
detect application-specific issues within their own code.

Differential Revision: http://llvm-reviews.chandlerc.com/D966

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187925 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/UsersManual.rst b/docs/UsersManual.rst
index 80956f8..bdcd471 100644
--- a/docs/UsersManual.rst
+++ b/docs/UsersManual.rst
@@ -895,6 +895,8 @@
       used in conjunction with the ``-fsanitize-undefined-trap-on-error``
       flag. This includes all of the checks listed below other than
       ``unsigned-integer-overflow`` and ``vptr``.
+   -  ``-fsanitize=dataflow``: :doc:`DataFlowSanitizer`, a general data
+      flow analysis.
 
    The following more fine-grained checks are also available: