Replace qlocaltime.cpp's qt_tzname() with qTzName() in
qtenvironmentvariables{_p.h,.cpp} so as to put the access to the
standard library global under the control of the same lock as controls
all Qt's calls to tzset() and functions that behave as if they called
it. This avoids UB on access to the global during a call to any of
these functions. Take care to use the lock only for the shortest time
needed.
This simplifies both callers and lets a QDTParser method escape to
qdatetimeparser.cpp to become a simple local static function instead
of a class method defined in a separate compilation unit.
Change-Id: I5ddee5641f2ed7b5676ece10375a1d5232eb7f22
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
b73dafbf86