Fix build break when running make src res

[intentionally-left-nil]

The file copies fail if the directory structure isn't created.

The AUR package https://aur.archlinux.org/packages/kwin-polonium is failing due to these errors without the fix

[zeroxoneafour]

make build is preferred to make src res. The only step added is zipping the file. If you really don't want to zip the file, run make res src with the res before the src. I will update the makefile to add $(PKGDIR) as a requirement for src though.

As a sidenote, I do not maintain the kwin-polonium or kwin-polonium-git pkgbuilds, they are for use at your own risk.

[intentionally-left-nil]

Confirmed that running make res src fixes the issue