std::make_unique is available in clang-3.4.1 with c++11

In file included from jsapi/qjsvalue.cpp:52:
In file included from jsruntime/qv4regexpobject_p.h:61:
In file included from jsruntime/qv4regexp_p.h:63:
In file included from ../3rdparty/masm/yarr/YarrInterpreter.h:29:
../3rdparty/masm/yarr/YarrPattern.h:315:31: error: call to 'make_unique' is ambiguous
 m_alternatives.append(std::make_unique<PatternAlternative>(this));
 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/v1/memory:3045:1: note: candidate function [with _Tp = JSC::Yarr::PatternAlternative, _Args = <JSC::Yarr::PatternDisjunction *>]
make_unique(_Args&&... __args)
^
../3rdparty/masm/stubs/wtf/Optional.h:90:19: note: candidate function [with T = JSC::Yarr::PatternAlternative, Args = <JSC::Yarr::PatternDisjunction *>]
 unique_ptr<T> make_unique(Args &&...args)
 ^
1 error generated.
*** [.obj/qjsvalue.o] Error code 1

make[2]: stopped in /wrkdirs/usr/ports/lang/qt5-qml/work/qtdeclarative-everywhere-src-5.12.0-beta3/src/qml
--- .obj/qv4compileddata.o ---
In file included from compiler/qv4compileddata.cpp:47:
In file included from ../../include/QtQml/5.12.0/QtQml/private/qv4regexpobject_p.h:1:
In file included from ../../include/QtQml/5.12.0/QtQml/private/../../../../../src/qml/jsruntime/qv4regexpobject_p.h:61:
In file included from jsruntime/qv4regexp_p.h:63:
In file included from ../3rdparty/masm/yarr/YarrInterpreter.h:29:
../3rdparty/masm/yarr/YarrPattern.h:315:31: error: call to 'make_unique' is ambiguous
 m_alternatives.append(std::make_unique<PatternAlternative>(this));
 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/v1/memory:3045:1: note: candidate function [with _Tp = JSC::Yarr::PatternAlternative, _Args = <JSC::Yarr::PatternDisjunction *>]
make_unique(_Args&&... __args)
^
../3rdparty/masm/stubs/wtf/Optional.h:90:19: note: candidate function [with T = JSC::Yarr::PatternAlternative, Args = <JSC::Yarr::PatternDisjunction *>]
 unique_ptr<T> make_unique(Args &&...args)
 ^
1 error generated.
*** [.obj/qv4compileddata.o] Error code 1