$portDir is not set or empty when used outside build chroot

[jmairboeck]

I found out when testing including a generated part of the recipe via source in the texlive recipe

https://github.com/haikuports/haikuports/blob/2d7c6ec0190fe8dc1fd438a58e6a5379f2fde895/app-text/texlive_texmf/texlive_texmf-2021.recipe#L57-L68

that $portDir is always empty or unset (did not specifically check which).

I think $portDir should point to the directory of the recipe, just like $portBaseDir, in contexts outside the chroot (which is the case when parsing the recipe for dependency infos). Inside the chroot, the current behavior of it being empty is fine.

The workaround I used in the recipe (checking whether $workDir is set) only works because $workDir is one of two variables that is only set in a "not forParsing" context (see https://github.com/haikuports/haikuporter/blob/master/HaikuPorter/Port.py#L1109-L1119).