[llvm] [regex][FileCheck] Support back-references up to 20. (PR #174150)

[Thomas Symalla via llvm-commits]

================
@@ -1,8 +1,6 @@
 ; RUN: FileCheck -input-file %s %s
-; XFAIL: *
+; XPASS: *
----------------
tsymalla wrote:

An XPASS test as per my understanding is a former XFAIL test that is now expected to pass since the former XFAIL has been fixed.
So, in practice, it seems like a semantical thing instead of being different to a simple RUN.

https://github.com/llvm/llvm-project/pull/174150