Yes, they were removed in Qt 5, as you noted yourself.
The reason is that these are functions only for Symbian, and such things simply confuse Qt users if they work only on a specific platform, especially if this platform is not even supported by Qt 5 in its essence.
gerrit :
https://codereview.qt-project.org/#change,11280
#if QT_VERSION < 0x040702
:
#if (QT_VERSION < QT_VERSION_CHECK(4, 7, 2)) || (QT_VERSION >= QT_VERSION_CHECK(5, 0, 0))
, Qt, :
#if (QT_VERSION < QT_VERSION_CHECK(4, 7, 2)) || (QT_VERSION >= QT_VERSION_CHECK(5, 0, 0))
...
#endif
, . , Qt , QtSerialPort.