comdlg32/tests: make sure to use a return value (LLVM/Clang)

[Austin English]

WTB reports some crashes for me (W2K8R2X64 / W7PROX64), seems to be a
compiler error. Uploading a prebuild executable works.

See https://testbot.winehq.org/JobDetails.pl?Key=12792 /
https://testbot.winehq.org/JobDetails.pl?Key=12794 /
https://testbot.winehq.org/JobDetails.pl?Key=12797

-- 
-Austin
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diff --git a/dlls/comdlg32/tests/itemdlg.c b/dlls/comdlg32/tests/itemdlg.c
index 208ec8c..adf4028 100644
--- a/dlls/comdlg32/tests/itemdlg.c
+++ b/dlls/comdlg32/tests/itemdlg.c
@@ -964,6 +964,7 @@ static void test_advise_helper(IFileDialog *pfd)
     ensure_zero_events(pfdeimpl);
 
     hr = IFileDialog_Unadvise(pfd, cookie[0]);
+    ok(hr == S_OK, "got 0x%08x\n", hr);
 
     if(0)
     {