Convert pagecache to python 3

First pass with '2to3', then fixups:
- Call python3 explicitly
- Remove redundant print((), ...) parentheses
- Use len() to compare filename < 64
- Convert Queue.get() bytes to string
- Handle ctrl-c without traceback

Bug: 342168858
Test: sudo apt install python-is-python3 && ./pagecache.py
Change-Id: Ie47ace7ed1ad620c77bb86955b6b60b0c57e047f
1 file changed