It's running into different behavior between OS versions, and it's getting
time-consuming and annoying to keep up with the changes.
So instead just remove the test, because as far as I can see it's not testing
something important anyway (we don't care exactly which library provides the
'mono_native_initialize' function, the important part is that it's callable,
which we already test elsewhere).
Fixes this when running on tvOS using dylibs:
> [FAIL] Introspection.CheckSymbols : dlsym() not found mono_native_initialize()
Now:
* If on iOS, we'll always have the `mono_native_initialize` symbol, because the symbol is used in P/Invoke in a user assembly (the test assembly itself), and mtouch will make the AOT-compiled code use dlsym for P/Invokes in user assemblies (and when using dlsym we can't (native) strip away the symbol).
* If on watchOS or tvOS, we'll have the symbol when we're loading `mono_native_initialize` from a dylib. If loading `mono_native_initialize` from a static library, we can (native) strip away the symbol because mtouch will make the AOT-compiled P/Invoke use a static reference to the native symbol, and thus the `mono_native_initialize` symbol will not be present in the executable.