Mac build issues: fix integer type agreement

Also removes some cases of meaninglessly-named variables being used over and over again in different ways.
Mac build issues: remove meaningless redundancies in string handling
Mac build issues: fix a broken format string
Mac: add missing files
Mac build issues: fix minor issues in OOCommodities
Niggles in OOCommodityMarket

* Correct name in header comment
* Use static for internal function
Xcode 6 compatibility

* Always use latest Mac OS X SDK
* Don't build fake poll() in libnspr
* Suppress auto-import warnings (applies to Xcode 5.1 too)