- This is a (weak/overridable) function meant to be called when the
program encounters an unrecoverable error, but it's not fatal enough
to bring down the entire system with it.
- The default implementation uses svcBreak, passing the result code
in the user buffer.
- Replaced all usages of fatalThrow with diagAbortWithResult throughout
the entire library.
This macro is only ever used with const input data within chachaInit(),
which causes -Wcast-qual warnings. This is trivial enough to fix, by
preserving the qualifier within the cast.
