We are currently using this value once before it's initialized, since we
check it before we set it in Clock::calendar_text(). This was caught by
Valgrind, producing the following error:
==8962== Conditional jump or move depends on uninitialised value(s)
==8962== at 0x138285: date::operator==(date::year_month_day const&, date::year_month_day const&) (date.h:2793)
==8962== by 0x135F11: waybar::modules::Clock::calendar_text[abi:cxx11](waybar::modules::waybar_time const&) (clock.cpp:111)
==8962== by 0x13587C: waybar::modules::Clock::update() (clock.cpp:62)
==8962== by 0x156EFA: waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)::{lambda()#1}::operator()() const (bar.cpp:577)
==8962== by 0x157F39: sigc::adaptor_functor<waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)::{lambda()#1}>::operator()() const (adaptor_trait.h:256)
==8962== by 0x157D94: sigc::internal::slot_call0<waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)::{lambda()#1}, void>::call_it(sigc::internal::slot_rep*) (slot.h:136)
==8962== by 0x5177B21: Glib::DispatchNotifier::pipe_io_handler(Glib::IOCondition) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==8962== by 0x517DB5B: Glib::IOSource::dispatch(sigc::slot_base*) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==8962== by 0x5188B96: Glib::Source::dispatch_vfunc(_GSource*, int (*)(void*), void*) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==8962== by 0x5CBC913: g_main_context_dispatch (in /usr/lib/libglib-2.0.so.0.6600.2)
==8962== by 0x5D107D0: ??? (in /usr/lib/libglib-2.0.so.0.6600.2)
==8962== by 0x5CBB120: g_main_context_iteration (in /usr/lib/libglib-2.0.so.0.6600.2)
Initialize the value to prevent the error.
Currently, the bottom border on workspace buttons eats into the box size
and causes the text to sit higher than in other modules. This is ugly
when there are other modules (like the window title) right next to the
workspace module. To fix the issue, create the bottom border using an
inset box-shadow, which doesn't affect the box's content sizing.