GUI no longer building by default

[Daniel J Sebald]

Rik,

I see you've made some changes with checking for GUI utilities:

3 days ago 	Rik 	build: Use AMCOND to build GUI editor if Qscintilla 
available.
3 days ago 	Rik 	build: Add more #ifdefs to build GUI when Qscintilla is 
not present.

I'm now getting the following:

configure:65665: checking for moc-qt5
configure:65695: result: no
configure:65665: checking for moc-qt4
configure:65681: found /usr/bin/moc-qt4
configure:65692: result: moc-qt4
configure:65707: checking for uic-qt5
configure:65737: result: no
configure:65707: checking for uic-qt4
configure:65723: found /usr/bin/uic-qt4
configure:65734: result: uic-qt4
configure:65749: checking for rcc
configure:65765: found /usr/bin/rcc
configure:65776: result: rcc
configure:65791: checking for lrelease
configure:65821: result: no
configure:65834: WARNING: Qt utility programs moc, uic, rcc, and 
lrelease not found -- disabling GUI

It would seem that the new thing, which isn't being found, is a 
definition (i.e., utility) for lrelease.  Is this lrelease something 
that is needed?  Is it simply a consequence of the AMCOND test?

On my system is lrelease-qt4, so I'm able to configure and build the GUI 
using:

[.]# ../octave/configure LRELEASE=lrelease-qt4

Should that name be added to the list of alternatives in configure? 
I.e., the following

    for ac_prog in lrelease

becomes

    for ac_prog in lrelease-qt5 lrelease-qt4 lrelease

similar to the following existing loop inside the configure script

    for ac_prog in moc-qt5 moc-qt4 moc

?

Dan