ole32/tests: Standardize the COM usage in clipboard.c.

[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
http://testbot.winehq.org/JobDetails.pl?Key=7585

Your paranoid android.


=== W2K8SE (32 bit clipboard) ===
clipboard: unhandled exception c0000005 at 769B7E6D

=== W7PRO (32 bit clipboard) ===
clipboard.c:1215: Test failed: got 80040064
clipboard.c:1216: Test failed: got 0

=== W7PROX64 (64 bit clipboard) ===
clipboard.c:1215: Test failed: got 80040064
clipboard.c:1216: Test failed: got 0