fix nullptr/boost compile error

error: no match for ternary ‘operator?:’ in
‘((writerfilter::dmapper::DomainMapper_Impl*)this)->writerfilter::dmapper::DomainMapper_Impl::m_aFieldStack.std::stack<_Tp,
_Sequence>::empty<boost::shared_ptr<writerfilter::dmapper::FieldContext>,
std::deque<boost::shared_ptr<writerfilter::dmapper::FieldContext>,
std::allocator<boost::shared_ptr<writerfilter::dmapper::FieldContext> > > >() ?
nullptr :
((writerfilter::dmapper::DomainMapper_Impl*)this)->writerfilter::dmapper::DomainMapper_Impl::m_aFieldStack.std::stack<_Tp,
_Sequence>::top<boost::shared_ptr<writerfilter::dmapper::FieldContext>,
std::deque<boost::shared_ptr<writerfilter::dmapper::FieldContext>,
std::allocator<boost::shared_ptr<writerfilter::dmapper::FieldContext> > > >()’

Change-Id: I76c7507390bcf80f6ca722c4eedfd65c9a46952f
fdo84315: add integration test for basic LibreOffice Base functionality

Thanks to Stephan for helping with the test environment setup:

sbergman@redhat.com:  Do the same "set UserInstallation to user profile dir in
test/user-template" in UnoInProcess's setUp as is done in
test::BootstrapFixtureBase::setUp (unotest/source/cpp/bootstrapfixturebase.cxx)
for CppunitTests.  That way, these tests all use the workdir/unittest/
UserInstallation concurrently, but they at least do not run into the gotcha in
SubstitutePathVariables::SetPredefinedPathVariables
(framework/source/services/substitutepathvars.cxx) to only set the
PREDEFVAR_USERPATH if PATH_EXISTS.

Change-Id: Iad058098a4c69cb567e2d3222af3c7d4ba993271