I have done hg update to incorporate the latest changes, and then
autoconf
./configure
Last time I built mxe-octave, my build didn't fail because of Qt (though GUI was disabled)
Log for octave:
checking for moc-qt5... no
checking for moc-qt4... no
checking for moc... no
checking for uic-qt5... no
checking for uic-qt4... no
checking for uic... no
checking for rcc... no
checking for lrelease-qt5... no
checking for lrelease-qt4... no
checking for lrelease... no
configure: WARNING: Qt utility programs moc, uic, rcc, and lrelease not found -- disabling GUI