neptune3-ui compilation issue

From the log:
agent:2019/02/18 11:30:50 build.go:192: clang: error: linker command failed with exit code 1 (use -v to see invocation)
agent:2019/02/18 11:30:50 build.go:192:
agent:2019/02/18 11:30:50 build.go:192: ** BUILD FAILED **
agent:2019/02/18 11:30:50 build.go:192:
agent:2019/02/18 11:30:50 build.go:192:
agent:2019/02/18 11:30:50 build.go:192: The following build commands failed:
agent:2019/02/18 11:30:50 build.go:192: Ld Debug-iphonesimulator/neptune3-ui.app/neptune3-ui normal x86_64
agent:2019/02/18 11:30:50 build.go:192: (1 failure)
agent:2019/02/18 11:30:50 build.go:192: make[2]: *** [xcodebuild-debug-simulator] Error 65
agent:2019/02/18 11:30:50 build.go:192: make[1]: *** [sub-neptune3-ui-make_first] Error 2
agent:2019/02/18 11:30:50 build.go:192: make[1]: *** Waiting for unfinished jobs....

Build log: https://testresults.qt.io/logs/qt-apps/neptune3-ui/aaf76ec012baa521b11fefbb317edd1d92f67466/MacOSMacOS_10_13x86_64IOSIOS_ANYmultiClangqtci-macos-10.13-x86_64-2-e1ab08DebugAndRelease_DisableTests_Static/17f1503c4933513eaacb010c74446a6079db4827/build_1550547270/log.txt.gz

Details: http://ci-files01-hki.intra.qt.io:8080/coin/integration/qt/tqtc-qt5/tasks/1550547231

Tested changes (refs/builds/qtci/tqtc/5.12/1550488519):
https://codereview.qt-project.org/#/q/6eac207e2fc2fb9a4a4a2388cb55321bdb267cc7,n,z Merge remote-tracking branch 'origin/5.12' into tqtc/5.12
https://codereview.qt-project.org/#/q/9f1f50febaa1d450055e193bad11542f9a67d53d,n,z Update submodules on 'tqtc/5.12' in qt5