This uses a recent but unannounced (also read as private) feature of
dyld where it ignores duplicate Objective-C classes when they're in a
special format in the binary. c8a445f88f/dyld/PrebuiltLoader.cpp (L1660-L1662)
I think this is generally safe because hopefully people aren't actually
using the SwiftSyntax classes through the Objective-C runtime, but if
they are we'd still probably prefer to silence the noise and accept the
UB.
Fixes https://github.com/realm/SwiftLint/issues/4782
Keith Smiley