TopContextDynamicData: Fix bug in loadPartialData

Detected using ASAN

Regression introduced by 49e4b656f0e54bff882f03efe04feedff5994ed1

31328==ERROR: AddressSanitizer: heap-buffer-overflow on address

0x60b0007dc6e4 at pc 0x7f8c81dd210f bp 0x7ffc0dba13f0 sp 0x7ffc0dba13e8
READ of size 8 at 0x60b0007dc6e4 thread T0

#0 0x7f8c81dd210e in

QList<KDevelop::IndexedDUContext>::node_construct(QList<KDevelop::IndexedDUContext>::Node*,
KDevelop::IndexedDUContext const&)
/usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:405:39

#1 0x7f8c81dd210e in

QList<KDevelop::IndexedDUContext>::append(KDevelop::IndexedDUContext
const&) /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:569

#2 0x7f8c81dd210e in

QList<KDevelop::IndexedDUContext>::operator<<(KDevelop::IndexedDUContext
const&) /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:355

#3 0x7f8c81dd210e in

KDevelop::TopDUContextDynamicData::loadImporters(unsigned
int)::$_0::operator()(KDevelop::TopDUContextData const*) const
/home/kfunk/devel/src/kf5/kdevplatform-stable/language/duchain/topducontextdynamicdata.cpp:505

#4 0x7f8c81dd210e in void (anonymous

namespace)::loadPartialData<KDevelop::TopDUContextDynamicData::loadImporters(unsigned
int)::$_0>(unsigned int,
KDevelop::TopDUContextDynamicData::loadImporters(unsigned int)::$_0)
/home/kfunk/devel/src/kf5/kdevplatform-stable/language/duchain/topducontextdynamicdata.cpp:175

#5 0x7f8c81dd210e in

KDevelop::TopDUContextDynamicData::loadImporters(unsigned int)
/home/kfunk/devel/src/kf5/kdevplatform-stable/language/duchain/topducontextdynamicdata.cpp:502

#6 0x7f8c81e7bc8d in KDevelop::ParsingEnvironmentFile::importers()

const
/home/kfunk/devel/src/kf5/kdevplatform-stable/language/duchain/parsingenvironment.cpp:205:11

#7 0x7f8c81d42a12 in

KDevelop::DUChainPrivate::addContextsForRemoval(QSet<unsigned int>&,
KDevelop::IndexedTopDUContext)
/home/kfunk/devel/src/kf5/kdevplatform-stable/language/duchain/duchain.cpp:1015:81

#8 0x7f8c81d12dd6 in KDevelop::DUChainPrivate::cleanupTopContexts()

/home/kfunk/devel/src/kf5/kdevplatform-stable/language/duchain/duchain.cpp:985:9

#9 0x7f8c81d08f64 in KDevelop::DUChain::shutdown()

/home/kfunk/devel/src/kf5/kdevplatform-stable/language/duchain/duchain.cpp:1572:5

#10 0x7f8c8a4e6c07 in KDevelop::Core::cleanup()

/home/kfunk/devel/src/kf5/kdevplatform-stable/shell/core.cpp:454:9

#11 0x7f8c8a4e5add in KDevelop::Core::shutdown()

...

AddressSanitizer can not describe address in more detail (wild memory
access suspected).
SUMMARY: AddressSanitizer: heap-buffer-overflow
/usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:405
QList<KDevelop::IndexedDUContext>::node_construct(QList<KDevelop::IndexedDUContext>::Node*,
KDevelop::IndexedDUContext const&)

Differential Revision: https://phabricator.kde.org/D845