Issues found by Coverity in Node.js

[targos]

Node.js benefits from free daily Coverity scans. Here are the current issues generated for ada:

Overflowed integer argument

Overflowed constant

Logically dead code

Variable copied when it could be moved

[lemire]

@targos Some of these appear to be clearly false positives. :-)

[anonrig]

I addressed some of them. I think the rest is false positive. We can close this issue. Thanks @targos