LINGER, RECONNECT_IVL and BACKLOG take 'int' instead of a sized primitive

[chuckremes]

When using integers from scripting environments (even under a 64-bit build) there can be disagreements on how the runtime environment defines an int versus what the library is expecting.

Just be specific and make those args int64_t so we can avoid any potential bugs.

[sustrik]

As 0MQ is heading towards BSD socket (POSIX) compliance, the 'int' seems more appropriate than 'int64_t'. In any case the types cannot be changed till version 3.0 (the change would break backward compatibility). The whole topic of socket option types have to be discussed in detail then. I'm closing the issue in the meantime.