configure fails with missing qmakespec for qtbase on Ubuntu 18.04

I fail to configure Qt 5.10.1 on Ubuntu 18.04. I've installed all prerequisites with

sudo apt-get build-dep libqt5core5a

Then I run configure with:

./configure -prefix "/data/thirdparty-bindir/qt"

But I get the error:

+ cd qtbase
+ /data/thirdparty/qt-everywhere-src-5.10.1/qtbase/configure -top-level -prefix /data/thirdparty-bindir/qt -platform linux-g++
Creating qmake...
...........................................................................................Done.
Could not find qmake configuration file .
Error processing project file: /data/thirdparty/qt-everywhere-src-5.10.1

It does not help if I explicitly set the qmakespec with -platform linux-g++, the result is the same.