comctl32: Fix handling of NULL text for TTM_ADDTOOLW.

[Alexandre Julliard]

Francois Gouget <fgouget at free.fr> writes:

> ---
>
> The __WINESRC__ patch introduced a new failure on all Windows platforms:
> http://test.winehq.org/data/tests/comctl32:tooltips.html
>
> Apparently passing a NULL string is ok with the ANSI version, but not 
> with the Unicode one.
>
>  dlls/comctl32/tests/tooltips.c |  2 +-
>  dlls/comctl32/tooltips.c       | 47 +++++++++++++++++++++++-------------------
>  2 files changed, 27 insertions(+), 22 deletions(-)

It breaks other tests:

../../../tools/runtest -q -P wine -T ../../.. -M comctl32.dll -p comctl32_test.exe.so status.c && touch status.ok
status.c:421: Test failed: Expected Tooltip Text, got 
make[1]: *** [status.ok] Error 1

-- 
Alexandre Julliard
julliard at winehq.org