[llvm] [FileCheck] Add a diff output option for FileCheck (PR #187120)

[Shivam Gupta via llvm-commits]

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@@ -2961,20 +2960,17 @@ bool FileCheck::checkInput(SourceMgr &SM, StringRef Buffer,
       // treated as a stray line. Even if a match is found later, we report
       // the gap as a mismatch.
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xgupta wrote:

Updated in latest commit https://github.com/llvm/llvm-project/pull/187120/changes/74782924e4699ad9eea14bdf2f41516f9436f895.

https://github.com/llvm/llvm-project/pull/187120