posix-*.c: remove some string copies in posix_handle_pump() and related functions

[mykaul]

posix-*.c: remove some string copies in posix_handle_pump() and related functions

- Remove multipls strncpy() from posix_handle_pump(), as well as an strotoul() call.
- Remove redundant 'ret' variable
- posix_handle_path() always gets PATH_MAX path variables, no need to pass size to it.
- Make functions static, etc.

[stale[bot]]

Thank you for your contributions. Noticed that this issue is not having any activity in last ~6 months! We are marking this issue as stale because it has not had recent activity. It will be closed in 2 weeks if no one responds with a comment here.

[mykaul]

Still hoping to get to do it.

[stale[bot]]

Thank you for your contributions. Noticed that this issue is not having any activity in last ~6 months! We are marking this issue as stale because it has not had recent activity. It will be closed in 2 weeks if no one responds with a comment here.