mk: pwd -P frequently used, problematic

[alarixnia]

-P is hardcoded in a few places in mk/ and some implementations don't support it, including gnu coreutils from the mid 2000s.

I don't get the point of being explicit with the -P flag. It limits our ability to support older operating systems.

[jperkin]

The reason is that buildlink/wrappers do not support symlinks, and we use -P to detect when this is broken, e.g.:

$ cd /tmp
$ pwd
/tmp
$ pwd -P
/private/tmp

We would need to find an alternative that supports every system.

[jperkin]

Hmm, I may have a workaround, that may even end up avoiding having to fork:

$ bmake MAKEOBJDIRPREFIX=. -v PWD
/private/tmp

[alarixnia]

It seems to just be old GNU pwd that's problematic. I was able to work around this by changing all references to pwd to /bin/pwd - that's set in tools/ already, but maybe there's dependency issues including it