Avoid use of "0" with tor_parse_foo()
The tor_parse_long() functions and family can behave a little different on different platforms when the underlying strto* functions behave differently. This is exacerbated by use of bases other than 10, as we found on legacy/trac#22789 (moved). Let's stop using "base 0" (the 'autodetect' base) anywhere in our code.