Fixed building for iOS.

[rizerco]

I’ve fixed the build for iOS, but the example now crashes on launch with the following error:

*** Assertion failure in Class _UIApplicationGetPrincipalClass(NSString *__strong)(), UIApplication.m:5111
*** -[NSAutoreleasePool release]: This pool has already been drained, do not release it (double release).
fatal runtime error: Rust cannot catch foreign exceptions

I’ve not been able to work out the cause, so any pointers there would be appreciated.

Thanks, Luke

[ryanmcgrath]

I think this might need a bit of extra work, but I'm gonna merge it since you did the work of hunting down a chunk of it - appreciate it!