Merging r293360:

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r293360 | gbiv | 2017-01-27 18:19:40 -0800 (Fri, 27 Jan 2017) | 11 lines

Change how we handle diagnose_if attributes.

This patch changes how we handle argument-dependent `diagnose_if`
attributes. In particular, we now check them in the same place that we
check for things like passing NULL to Nonnull args, etc. This is
basically better in every way than how we were handling them before. :)

This fixes PR31638, PR31639, and PR31640.

Differential Revision: https://reviews.llvm.org/D28889

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Merging r293369:
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r293369 | gbiv | 2017-01-27 20:16:32 -0800 (Fri, 27 Jan 2017) | 7 lines

Attempt to unbreak buildbots.

r293360 broke some ARM bots, because size_t on those targets is
apparently `unsigned int`, not `unsigned long`. `sizeof(whatever)`
should to give us a `size_t`, so we can just use the type of that
instead.

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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_40@293784 91177308-0d34-0410-b5e6-96231b3b80d8