[PATCH] Implement bad cast checks using control flow integrity information.

[Kostya Serebryany]

Please also add compiler-rt test(s)


================
Comment at: docs/UsersManual.rst:971
@@ -970,1 +970,3 @@
       where the array bound can be statically determined.
+   -  ``-fsanitize=cfi-dcast``: Base-to-derived cast to the wrong
+      dynamic type. Implies ``-flto``.
----------------
Don't we want more verbose names? 
cfi-polymorphic-base-downcast 
cfi-void-to-polymorphic-cast
 or something.

http://reviews.llvm.org/D8312

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