Do not set C++ compiler explicitly in Xcode projects

LLVM-GCC is no longer available in Xcode 5 (on OS X 10.9).
Backport patch to remove strlcat from curl

Since strlcat is defined in OS X 10.9 as a macro, it collides with
the fallback definition in curl. I backported this fix from upstream
curl: http://curl.haxx.se/mail/lib-2013-02/0214.html

Originally I intended to update curl to a more recent version instead,
but I did not want to break the other platform builds.
Include unistd.h for usleep on OS X 10.9
Set 32-bit architecture on OS X
Use GNU libstdc++ instead of libc++ on OS X
Remove LuaJIT dependency from non-LuaJIT iOS target
Ignore Xcode 5 .xccheckout files
Merge pull request #800 from theGoodEvil/xcode5-compat

Xcode 5 / OS X 10.9 Compatibility