user32: Hide horizontal Listbox scroll bar if no horizontal extent is set.

[Joachim Priesner]

Am Freitag, 24. Juli 2015 schrieb 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=15534
> 
> Your paranoid android.
> 
> 
> === wvistau64 (32 bit listbox) ===
> listbox.c:709: Test failed: SendMessage(LB_DIR, DDL_DIRECTORY, *) filled with 7 entries, expected > 7
> listbox.c:944: Test failed: SendMessage(LB_DIR, DDL_DIRECTORY|DDL_EXCLUSIVE, *) failed err 18
> 
> === wvistau64 (64 bit listbox) ===
> listbox.c:709: Test failed: SendMessage(LB_DIR, DDL_DIRECTORY, *) filled with 7 entries, expected > 7
> listbox.c:944: Test failed: SendMessage(LB_DIR, DDL_DIRECTORY|DDL_EXCLUSIVE, *) failed err 18

Unrelated failures.