[clang] [NFC][Clang] Use range for loops in ClangDiagnosticsEmitter (PR #115573)

[Rahul Joshi via cfe-commits]

jurahul wrote:

Its not clear to me if the failure is real or intermittent:

FAILURE
Failed to match LIBC_NAMESPACE::mkdirat(AT_FDCWD, TEST_DIR, S_IRWXU) against Succeeds(0).
Expected return value to be equal to 0 but got -1.
Expected errno to be equal to "Success" but got "File exists".


https://github.com/llvm/llvm-project/pull/115573