In DNBArchImplARM64.cpp I'm doing
```
#if __has_feature(ptrauth_calls) && defined(__LP64__)
```
And the preprocessor warns that this is not defined behavior. This
checks if ptrauth_calls is available and if this is being compiled
64-bit (i.e. arm64e), and defines a single DEBUGSERVER_IS_ARM64E when
those are both true.
I did have to duplicate one DNBLogThreaded() call which itself is a
macro, and using an ifdef in the middle of macro arguments also got me a
warning from the preprocessor.
While testing this for all the different targets, I found a DNBError
initialization that accepts a c-string but I'm passing in a printf-style
formatter c-string and an argument. Create the string before the call
and pass in the constructed string.
rdar://127129242