shell32/tests: Fix an ok() call so it shows which DDE test caused the failure.

[Marvin]

Hi,

While running your changed tests on Windows, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?
Full results can be found at
https://testbot.winehq.org/JobDetails.pl?Key=20416

Your paranoid android.


=== wvistau64 (64 bit shlexec) ===
shlexec.c:2178: Test failed: ShellExecuteEx(mask="0x808040", file="C:/Users/winetest/AppData/Local/Temp/wtD2D8.tmp/test_shortcut_exe.lnk") WaitForSingleObject(hProcess) returned 258
shlexec.c:2178: Test failed: ShellExecuteEx(mask="0x808040", file="C:/Users/winetest/AppData/Local/Temp/wtD2D8.tmp/test_shortcut_exe.lnk") child returned 259