[llvm] [ctx_prof] Fix checks in `PGOCtxprofFlattening` (PR #108467)

[David Li via llvm-commits]

================
@@ -0,0 +1,54 @@
+; RUN: split-file %s %t
+; RUN: llvm-ctxprof-util fromJSON --input=%t/profile.json --output=%t/profile.ctxprofdata
----------------
david-xl wrote:

describe the purpose of the test?

https://github.com/llvm/llvm-project/pull/108467