[PATCH] ole32/tests: Add some return value checks (Coverity).

[Marvin]

Hi,

While running your changed tests, 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=62825

Your paranoid android.


=== debian10 (32 bit French report) ===

ole32:
clipboard.c:864: Test failed: didn't find cf_dataobject
clipboard.c:865: Test failed: didn't find cf_ole_priv_data
clipboard.c:626: Test failed: got 800401d0
clipboard.c:1019: Test failed: failed to clear clipboard, hr = 0x800401d0.
clipboard.c:626: Test failed: got 800401d0
clipboard.c:1029: Test failed: expected data_cmpl ref=0, got 4