Merging r367134:

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r367134 | nathan-huckleberry | 2019-07-26 19:29:35 +0200 (Fri, 26 Jul 2019) | 16 lines

[Sema] Fix -Wuninitialized for struct assignment from GNU C statement expression

Summary:
Do not automatically report self references of structs in statement expression
as warnings. Instead wait for uninitialized cfg analysis.
https://bugs.llvm.org/show_bug.cgi?id=42604

Reviewers: aaron.ballman, rsmith, nickdesaulniers

Reviewed By: aaron.ballman, nickdesaulniers

Subscribers: nathanchance, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64678
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llvm-svn: 367150