config: address a number of Coverity issues

[kevans]

Summary

Highlights:

• Various memory leaks
• FILE* leaks
• tsize in moveifchanged() is only needed if !changed, and from_sb is only valid if !changed.
• Simplify trivially true expression
• Sanity check elfdump size output (+ fix variable sizes) (des@)

CID: 1471167, 1006391, 1505279, 1505333, 1505271, 1505275, 1505349
CID: 1505306, 1505232

[imp]

These changes look good, same comments about chunking, and I don't understand the path() changes... they seem to be spread over all these comits and I'm missing the connections to the other things... they might be better as a separate commit combining them all since that seems to be self contained... Or there needs to be a callout more explicitly in the commit message providing the context I'm clearly missing.

usr.sbin/config/main.cc

694

These changes aren't in the commit log, and look to be independent of all the others

usr.sbin/config/mkoptions.cc

311

another of this pattern... Unsure how it relates to the commit message.

[emaste]

Agree with @imp these are all pretty straightforward changes but I would split them out

[kevans]

usr.sbin/config/main.cc

694

Glossed over as "various memory leaks" because path() allocates memory that we drop on the floor, but I can separate these out into a separate commit since it's a common issue with handling its return value.