[PATCH 2/4] comctl32/monthcal: Fix the way a first day of week is handled

[Nikolay Sivov]

There's a difference between day of week enumeration in locale defined data and
SYSTEMTIME structure. Locale days are (Monday == 0) based while SYSTEMTIME
uses (Sunday == 0) base.

This patch implements a to/from conversion between these representations. Dates are
stored currently as SYSTEMTIMEs, so conversion only used in get/set helpers.

Another issue here is about negative first day of week value. Native control goes
crazy when this base day is set to (<= -2). Actually it does display current month and garbage
for previous. Currently Wine code doesn't fully support this behaviour, but it isn't
a problem at this point. To reflect get/set behaviour exception is made for
negative values - they are stored intact (FIXME added for that case).

Changelog:
    - fix the way a first day of week is handled