When destroying the static vcl::CommandInfoProvider aProvider from
vcl::CommandInfoProvider::Instance (vcl/source/helper/commandinfoprovider.cxx)
during exit, it releases its mxCachedGlobalAcceleratorConfiguration reference on
GlobalAcceleratorConfiguration
(framework/source/accelerators/globalacceleratorconfiguration.cxx), which may
get destroyed, whose base class framework::XCUBasedAcceleratorConfiguration
(framework/source/inc/accelerators/acceleratorconfiguration.hxx) has a
salhelper::SingletonRef<framework::KeyMapping> member, whose destructor
(include/salhelper/singletonref.hxx) uses
salhelper::SingletonRef<framework::KeyMapping>::SingletonLockInit::operator ()'s
static osl::Mutex aInstance.

If, during construction, the instantiation of
salhelper::SingletonRef<framework::KeyMapping>::SingletonLockInit::operator ()'s
static osl::Mutex aInstance finishes before the instantiation of
vcl::CommandInfoProvider::Instance's static vcl::CommandInfoProvider aProvider,
the corresponding atexit cleanup actions will be recorded in the right order,
causing the above chain of calls to find the static Mutex still alive when used
from within the static CommandInfoProvider's destruction.

However, vcl::CommandInfoProvider's mxCachedGlobalAcceleratorConfiguration is
only set to css::ui::GlobalAcceleratorConfiguration::create in
vcl::CommandInfoProvider::GetGlobalAcceleratorConfiguration, so the
instantiation of the static Mutex instance can finish after the instantiation of
the static CommandInfoProvider instance, recording the atexit cleanup actions in
the wrong order, causing the static Mutex to be used after destruction.

This occasionally caused PythonTest_sfx2_python to hang during exit for me on
Linux, where trying to lock a destroyed pthread mutex can apparently deadlock.

rtl::Static does away with the need to do anything in the destructor, at the
expense of always keeping the instance alive until exit (and not being able to
recreate an already destroyed instance during exit, but code that would require
that behavior would probably already be broken to begin with), so the order of
creation of the CommandInfoProvider and GlobalAcceleratorConfiguration instances
becomes less of a concern.

Change-Id: Id6e3860ad9e5b7045980a0b9bf9eaef2e24129bb