[PATCH] Implement nonnull-attribute sanitizer

[Richard Smith]

One diagnostic quality comment, otherwise this looks fine.

================
Comment at: projects/compiler-rt/lib/ubsan/ubsan_handlers.cc:365
@@ +364,3 @@
+  if (!Data->DeclLoc.isInvalid())
+    Diag(Data->DeclLoc, DL_Note, "function declared here");
+}
----------------
It would seem better to point to the attribute rather than just to the function.

http://reviews.llvm.org/D5082