Fix Issue with Mac Compilation
Fix Issue with Mac Compilation

On the Mac, TARGET_OS_IPHONE is defined (but it’s defined as 0), so
this #ifdef will always resolve to true. A standard #if should be fine
to switch between iOS and Mac.
mxcl/PromiseKit,allen-zeng/PromiseKit,mxcl/PromiseKit,allen-zeng/PromiseKit,mxcl/PromiseKit,pgherveou/PromiseKit,pgherveou/PromiseKit,pgherveou/PromiseKit