doc: make gendoc.py module import policy aware
Without this, running gendoc.py during an install without C modules
available (via `make local`) will result in an import failure because
the default module load policy insists on C modules.
We also remove the sys.path adjustment because it is no longer needed
since our magic importer handles things.
Ancestors of 5
4 2 0
Ancestors of 6 and 5
3 4 2 1 0
Ancestors of 5 and 4
4 2 0
Ancestors of 7, stop at 6
6
Ancestors of 7, including revs
7 6 5 3 4 2 1 0
Ancestors of 7, 5 and 3, including revs
7 5 3 6 4 2 1 0
Descendants of 5
7 8
Descendants of 5 and 3
6 7 8
Descendants of 5 and 4
5 7 8