[PATCH][ASan] Link with the dynamic ASan library on iOS

Hi,

This patch enables the -faddress-sanitizer link-time flag for the iOS target.
The executable will be linked with libclang_rt.asan_osx_dynamic.dylib

I don't want to add this feature to the documentation until we make
sure it doesn't crash at runtime, but I think it's the right thing to
start with.

asan-ios.patch (657 Bytes)

I'm going to land this tomorrow if nobody objects.