QCoreApplication::library path, ensure mutex lock ordering

Do not keep the libraryPathMutex locked while calling QFactoryLoader::refreshAll
QFactoryLoader also lock a mutex, and recurse into QCoreApplication::libraryPath

Reviewed-by: Brad

Helgrind warning for reference:

==8442== Thread #1: lock order "0xDEBA470 before 0xDF63600" violated
==8442==    at 0x4C2911E: QMutex::lock() (in /usr/lib/valgrind/vgpreload_helgrind-amd64-linux.so)
==8442==    by 0x7EE5870: QMutexLocker::QMutexLocker(QMutex*) (qmutex.h:102)
==8442==    by 0x8025A8E: QCoreApplication::libraryPaths() (qcoreapplication.cpp:2234)
==8442==    by 0x8006FDC: QFactoryLoader::update() (qfactoryloader.cpp:109)
==8442==    by 0x8006F32: QFactoryLoader::QFactoryLoader(char const*, QString const&, Qt::CaseSensitivity) (qfactoryloader.cpp:99)
==8442==    by 0x6DE4351: qt_guiPlatformPlugin() (qguiplatformplugin.cpp:101)
==8442==    by 0x6DE7A5B: QApplicationPrivate::x11_apply_settings() (qapplication_x11.cpp:934)
==8442==    by 0x6DE9BAD: qt_set_x11_resources(char const*, char const*, char const*, char const*) (qapplication_x11.cpp:1111)
==8442==    by 0x6DF0CB3: qt_init(QApplicationPrivate*, int, _XDisplay*, unsigned long, unsigned long) (qapplication_x11.cpp:2323)
==8442==    by 0x6D4EF4D: QApplicationPrivate::construct(_XDisplay*, unsigned long, unsigned long) (qapplication.cpp:793)
==8442==    by 0x6D4EABE: QApplication::QApplication(int&, char**, int) (qapplication.cpp:712)
==8442==    by 0x41350F: main (tst_examples.cpp:227)
==8442==   Required order was established by acquisition of lock at 0xDEBA470
==8442==    at 0x4C2911E: QMutex::lock() (in /usr/lib/valgrind/vgpreload_helgrind-amd64-linux.so)
==8442==    by 0x7EE5870: QMutexLocker::QMutexLocker(QMutex*) (qmutex.h:102)
==8442==    by 0x8025FC3: QCoreApplication::addLibraryPath(QString const&) (qcoreapplication.cpp:2335)
==8442==    by 0x6DE792D: QApplicationPrivate::x11_apply_settings() (qapplication_x11.cpp:927)
==8442==    by 0x6DE9BAD: qt_set_x11_resources(char const*, char const*, char const*, char const*) (qapplication_x11.cpp:1111)
==8442==    by 0x6DF0CB3: qt_init(QApplicationPrivate*, int, _XDisplay*, unsigned long, unsigned long) (qapplication_x11.cpp:2323)
==8442==    by 0x6D4EF4D: QApplicationPrivate::construct(_XDisplay*, unsigned long, unsigned long) (qapplication.cpp:793)
==8442==    by 0x6D4EABE: QApplication::QApplication(int&, char**, int) (qapplication.cpp:712)
==8442==    by 0x41350F: main (tst_examples.cpp:227)
==8442==   followed by a later acquisition of lock at 0xDF63600
==8442==    at 0x4C2911E: QMutex::lock() (in /usr/lib/valgrind/vgpreload_helgrind-amd64-linux.so)
==8442==    by 0x7EE5870: QMutexLocker::QMutexLocker(QMutex*) (qmutex.h:102)
==8442==    by 0x80086A9: QFactoryLoader::refreshAll() (qfactoryloader.cpp:249)
==8442==    by 0x802607E: QCoreApplication::addLibraryPath(QString const&) (qcoreapplication.cpp:2344)
==8442==    by 0x6DE792D: QApplicationPrivate::x11_apply_settings() (qapplication_x11.cpp:927)
==8442==    by 0x6DE9BAD: qt_set_x11_resources(char const*, char const*, char const*, char const*) (qapplication_x11.cpp:1111)
==8442==    by 0x6DF0CB3: qt_init(QApplicationPrivate*, int, _XDisplay*, unsigned long, unsigned long) (qapplication_x11.cpp:2323)
==8442==    by 0x6D4EF4D: QApplicationPrivate::construct(_XDisplay*, unsigned long, unsigned long) (qapplication.cpp:793)
==8442==    by 0x6D4EABE: QApplication::QApplication(int&, char**, int) (qapplication.cpp:712)
==8442==    by 0x41350F: main (tst_examples.cpp:227)a

1 files changed, 2 insertions, 0 deletions

diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 0a5e06e..512e193 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -2308,6 +2308,7 @@ void QCoreApplication::setLibraryPaths(const QStringList &paths)
     if (!coreappdata()->app_libpaths)
         coreappdata()->app_libpaths = new QStringList;
     *(coreappdata()->app_libpaths) = paths;
+    locker.unlock();
     QFactoryLoader::refreshAll();
 }
 
@@ -2341,6 +2342,7 @@ void QCoreApplication::addLibraryPath(const QString &path)
     if (!canonicalPath.isEmpty()
         && !coreappdata()->app_libpaths->contains(canonicalPath)) {
         coreappdata()->app_libpaths->prepend(canonicalPath);
+        locker.unlock();
         QFactoryLoader::refreshAll();
     }
 }