[NetBSD] two fixes for swap code

[0-wiz-0]

Summary

• OS: NetBSD
• Bug fix: yes
• Type: core
• Fixes: -

Description

Fixes swap reporting on machines with lots of swap.

Before:

>>> import psutil
>>> psutil.swap_memory()
sswap(total=-170917888, used=5307994112, free=-5478912000, percent=-3105.6, sin=0, sout=528124133376)

After:

>>> import psutil
>>> psutil.swap_memory()
sswap(total=476570451968, used=5305618432, free=471264833536, percent=1.1, sin=0, sout=528124133376)

[giampaolo]

Can you please update README and CREDITS?

[0-wiz-0]

I've updated HISTORY and CREDITS, I hope that's what you meant - not sure what I should edit in README.

[giampaolo]

Merged. Thank you Thomas.