[REG 5.15.2 -> 6.0.3] Cannot build docs with static build of Qt

1. Configure Qt to build statically:

   ~/dev/src/qt-6.0.3/configure -release -static -prefix $PWD/qtbase -skip webengine -opensource -confirm-license -nomake examples -nomake tests
   

2. Build it:

   cmake --build . --parallel
   

3. Build the documentation:

   ninja -j1 docs
   

   It will fails with the error message:

   [106/140] cd /home/qtrob/dev/g++-10.2....nowebengine-rs/qtbase/./doc/qtcore.qch
   FAILED: qtbase/src/corelib/CMakeFiles/qch_top_level_docs_Core 
   cd /home/qtrob/dev/g++-10.2.0/qt-6.0.3-nowebengine-rs/qtbase/src/corelib && /home/qtrob/dev/g++-10.2.0/qt-6.0.3-nowebengine-rs/qtbase/bin/qhelpgenerator /home/qtrob/dev/g++-10.2.0/qt-6.0.3-nowebengine-rs/qtbase/./doc/qtcore/qtcore.qhp -o /home/qtrob/dev/g++-10.2.0/qt-6.0.3-nowebengine-rs/qtbase/./doc/qtcore.qch
   Warning: Ignoring WAYLAND_DISPLAY on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.
   qt.qpa.plugin: Could not find the Qt platform plugin "minimal" in ""
   This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
   
   Available platform plugins are: xcb, xcb, xcb, xcb, xcb, xcb, xcb, xcb, xcb, xcb.
   
   ninja: build stopped: subcommand failed.
   

All of the above succeeds when I remove "-static" from the call to configure.