shell32/tests: Return early if the shell folder creation fails in order to avoid a compiler warning.

[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=29562

Your paranoid android.


=== wvistau64 (32 bit shlfolder) ===
shlfolder.c:457: Test failed: 0: got 7480017f expected 7080017f
shlfolder.c:457: Test failed: 1: got f480017f expected 7080017f
shlfolder.c:457: Test failed: 2: got 44400177 expected 40400177
shlfolder.c:457: Test failed: 3: got 44400177 expected 40400177
shlfolder.c:457: Test failed: 4: got 44400177 expected 40400177

=== wvistau64 (64 bit shlfolder) ===
shlfolder.c:457: Test failed: 0: got 7480017f expected 7080017f
shlfolder.c:457: Test failed: 1: got f480017f expected 7080017f
shlfolder.c:457: Test failed: 2: got 44400177 expected 40400177
shlfolder.c:457: Test failed: 3: got 44400177 expected 40400177
shlfolder.c:457: Test failed: 4: got 44400177 expected 40400177