Sorry, this is somewhat off-topic, but it’s related to the apparent refusal of the responsible Arch maintainer to follow the build instructions:
Arch is fighting tooth and nail to remain the distribution from which we receive the highest percentage of Linux bug reports here for well over three years now.
The joke so far is, and hopefully remains to be, the maintainers of Arch based distros, interestingly, seem to be able to read carefully, because most of them had working Krita builds in the same period!
But hey, at least Arch can always claim they have the highest build numbers in their repo, which seems to be their main goal (our distros edge bleeds the most 
). That these not necessarily have to work is another story - and they don’t care about it.
But anyone who uses Arch to work productively - or even to make a living - is beyond help anyway. I suppose you could call that actively refusing to acknowledge reality - or self-destructive behavior. 
For productivity, make your living, you better use SUSE Linux Enterprise Desktop or the desktop version of RHEL.
Michelist