moc segfaults in CI

Module "qt/qtquickcontrols" (6c554465d66a6f80779d9eb96061691381c4dcdf) did not compile:
 /Users/qt/work/install/bin/moc -DQT_NO_EXCEPTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DQT_PLUGIN -DQT_QUICK_LIB -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB --include .moc/moc_predefs.h -I/Users/qt/work/install/mkspecs/macx-clang -I/Users/qt/work/qt/qtquickcontrols/tests/auto/testplugin -I/Users/qt/work/install/lib/QtQuick.framework/Headers -I/Users/qt/work/install/lib/QtGui.framework/Headers/5.9.0 -I/Users/qt/work/install/lib/QtGui.framework/Headers/5.9.0/QtGui -I/Users/qt/work/install/lib/QtWidgets.framework/Headers -I/Users/qt/work/install/lib/QtGui.framework/Headers -I/Users/qt/work/install/lib/QtQml.framework/Headers -I/Users/qt/work/install/lib/QtNetwork.framework/Headers -I/Users/qt/work/install/lib/QtCore.framework/Headers/5.9.0 -I/Users/qt/work/install/lib/QtCore.framework/Headers/5.9.0/QtCore -I/Users/qt/work/install/lib/QtCore.framework/Headers -I/usr/local/include -I/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1 -I/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/7.0.2/include -I/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include -F/Users/qt/work/install/lib ../shared/testmodel.h -o .moc/moc_testmodel.cpp
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -c -pipe -stdlib=libc++ -O2 -std=gnu++11  -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk -mmacosx-version-min=10.10 -fno-exceptions -Wall -W -fPIC -DQT_NO_EXCEPTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DQT_PLUGIN -DQT_QUICK_LIB -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/Users/qt/work/install/lib/QtQuick.framework/Headers -I/Users/qt/work/install/lib/QtGui.framework/Headers/5.9.0 -I/Users/qt/work/install/lib/QtGui.framework/Headers/5.9.0/QtGui -I/Users/qt/work/install/lib/QtWidgets.framework/Headers -I/Users/qt/work/install/lib/QtGui.framework/Headers -I/Users/qt/work/install/lib/QtQml.framework/Headers -I/Users/qt/work/install/lib/QtNetwork.framework/Headers -I/Users/qt/work/install/lib/QtCore.framework/Headers/5.9.0 -I/Users/qt/work/install/lib/QtCore.framework/Headers/5.9.0/QtCore -I/Users/qt/work/install/lib/QtCore.framework/Headers -I.moc -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks/OpenGL.framework/Headers -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks/AGL.framework/Headers -I/usr/local/opt/openssl/include -I/Users/qt/work/install/mkspecs/macx-clang -F/Users/qt/work/install/lib -o .obj/moc_testmodel.o .moc/moc_testmodel.cpp
 /Users/qt/work/install/bin/moc -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DQT_TESTLIB_LIB -DQT_CORE_LIB -DQT_TESTCASE_BUILDDIR='"/Users/qt/work/qt/qtquickcontrols/tests/auto/qquicktreemodeladaptor"' --include .moc/moc_predefs.h -I/Users/qt/work/install/mkspecs/macx-clang -I/Users/qt/work/qt/qtquickcontrols/tests/auto/qquicktreemodeladaptor -I/Users/qt/work/qt/qtquickcontrols/src/controls/Private -I/Users/qt/work/install/lib/QtTest.framework/Headers -I/Users/qt/work/install/lib/QtCore.framework/Headers -I/usr/local/include -I/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1 -I/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/7.0.2/include -I/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include -F/Users/qt/work/install/lib ../shared/testmodel.h -o .moc/moc_testmodel.cpp
 make[2]: *** [.moc/moc_testmodel.cpp] Segmentation fault: 11
 make[1]: *** [sub-qquicktreemodeladaptor-make_first] Error 2
 make: *** [sub-auto-make_first] Error 2
 Build log: http://testresults.qt.io/logs/qt/qtquickcontrols/e3180ae7b82a024966036b2f4da65f14b2bc8633/MacOSOSX_10_10x86_64MacOSOSX_10_10x86_64Clangqtci-osx-10.10-x86_64-71d782DebugAndRelease_Release/d0c1d3a2639ddd9e495da9910bc45d6f6e8bee02/testrun_1488353998/testlog.txt.gz
 Details: http://testresults.qt.io/coin/integration/qt/qtquickcontrols/tasks/1488353998
 Tested changes (refs/builds/qtci/5.9/1488353997):
   https://codereview.qt-project.org/#/q/ec62e1f98197f26a4957423cdfa25fb322260f65,n,z "to the empty string" => "to an empty string"
   https://codereview.qt-project.org/#/q/59660e01fb725c21b9bae6b0b76dcb52e353c7db,n,z Note that iconName requires QApplication