[clang] [Format] Configure ASSIGN_OR_RETURN macros for Google style (PR #169037)

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@@ -9,6 +9,7 @@
 #include "clang/Format/Format.h"
 
 #include "llvm/Support/VirtualFileSystem.h"
+#include "gmock/gmock.h"
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owenca wrote:

Undo. (See below.)

https://github.com/llvm/llvm-project/pull/169037