Ok this is now fixed in the latest git master. As a bonus, you now get a nifty resource monitor that shows up for builds longer than a minute ("Build time 207 min, peak load 3.59, peak memory 1256M, peak tmp 3515M" below.)
Thanks for the help
Code:
Starting libraries/qt5 (add version 5.7.1) ---------------------------- 23:02:58
Testing SlackBuild files ... done.
Verifying source files ... done.
Testing download URLs ... done.
Installing dependencies ...
libinput-1.7.0-i686-1_vm: Input device library ......................... [4.7M]
libxkbcommon-0.6.1-i686-1_vm: library to handle keyboard descriptions .. [1.8M]
Running qt5.SlackBuild ...
env MAKEFLAGS='-j4 -l3' nice -n 5 fakeroot bash ./qt5.SlackBuild
Build time 207 min, peak load 3.59, peak memory 1256M, peak tmp 3515M
Built ok: qt5-5.7.1-i686-1_vm.txz 02:30:44
Testing package qt5-5.7.1-i686-1_vm.txz ... done.
Test installing qt5-5.7.1-i686-1_vm.txz ...
qt5-5.7.1-i686-1_vm: a multi-platform C++ graphical user interface toolk [271M]
Running profile script: /etc/profile.d/qt5.sh
Unmounting chroot ... done.
:-) libraries/qt5 Added version 5.7.1 (a multi-platform C++ graphical user interface toolkit) (-: