Ok so 4.2.6 package followed compile steps (./configure, make). No problems at configure but unfortunately make end up with couple errors. Tried 4.3 and has been compiled without issues.
4.2 output:
root@plex:/home/Desktop/w/tvheadend-4.2.6# make
make -f Makefile.webui LANGUAGES="ach ady ar bg cs da de en_US en_GB es et fa fi fr he hr hu it ko lv lt nl no pl pt ro ru sl sk sq sv tr uk zh zh-Hans" all
make[1]: Entering directory '/home/rav/Desktop/w/tvheadend-4.2.6'
make -f Makefile.webui WEBUI=std compile-std
make[2]: Entering directory '/home/Desktop/w/tvheadend-4.2.6'
make[2]: *** No rule to make target 'src/webui/static/extjs/adapter/ext/ext-base.js', needed by 'src/webui/static/tvh.js.gz'. Stop.
make[2]: Leaving directory '/home/Desktop/w/tvheadend-4.2.6'
Makefile.webui:230: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory '/home/Desktop/w/tvheadend-4.2.6'
Makefile:762: recipe for target 'make_webui' failed
make: *** [make_webui] Error 2