error: 'O_RDONLY' was not declared in this scope

/home/qt/work/qt/qtdeclarative/src/qml/memory/qv4stacklimits.cpp: In function 'QV4::StackProperties QV4::stackProperties()':
/home/qt/work/qt/qtdeclarative/src/qml/memory/qv4stacklimits.cpp:208:43: error: 'O_RDONLY' was not declared in this scope
     const int fd = open("/proc/self/ctl", O_RDONLY);
                                           ^~~~~~~~
/home/qt/work/qt/qtdeclarative/src/qml/memory/qv4stacklimits.cpp:208:43: note: suggested alternative: 'QT7_ONLY'
     const int fd = open("/proc/self/ctl", O_RDONLY);
                                           ^~~~~~~~
                                           QT7_ONLY
/home/qt/work/qt/qtdeclarative/src/qml/memory/qv4stacklimits.cpp:208:20: error: 'open' was not declared in this scope
     const int fd = open("/proc/self/ctl", O_RDONLY);
                    ^~~~
/home/qt/work/qt/qtdeclarative/src/qml/memory/qv4stacklimits.cpp:208:20: note: suggested alternative: 'popen'
     const int fd = open("/proc/self/ctl", O_RDONLY);
                    ^~~~
                    popen