Fix _stdlib_getErrorDefaultUserInfo to have the signature the runtime expects.
Fix _stdlib_getErrorDefaultUserInfo to have the signature the runtime expects.

The ABI mismatch here would cause a crash in cases when the Foundation overlay wasn't available, or its implementation of swift_Foundation_getErrorDefaultUserInfo wasn't dynamically resolvable, such as in a stripped statically linked binary. Fixes rdar://problem/29173132.

apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation