doc/interpreter/octave_interpreter.qch fails on ubnutu 16.04 in stable branch

[Tatsuro MATSUOKA]

I tried recent stable snapshot. (16155531bda4) 


GEN      doc/interpreter/octave_interpreter.qch
qcollectiongenerator: could not exec 
'/usr/lib/x86_64-linux-gnu/qt4/bin/qcollectiongenerator': No such file or 
directory
Makefile:27894: recipe for target 'doc/interpreter/octave_interpreter.qch' 
failed
make[2]: *** [doc/interpreter/octave_interpreter.qch] Error 1
make[2]: Leaving directory '/home/mousei7/work/Octave/octave-hg/octave'
Makefile:26512: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/home/mousei7/work/Octave/octave-hg/octave'
Makefile:10167: recipe for target 'all' failed
make: *** [all] Error 2


I have configured with qt5.


Perhaps my setting qt on ubuntu 16.04 is wrong. 

Any suggestions?