[SE-0112] Make NSCustomError.errorDomain static.
[SE-0112] Make NSCustomError.errorDomain static.

The error domain is meant to identify the type; it cannot meaningfully vary.

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