Unbreak the build with Clang on architectures where JACK uses non-packed
data structures, like arm64 or powerpc. The alignment errors are exposed
there because:
* The non-packed data structures require 8 byte alignment.
* alignas() is not allowed to weaken alignment requirements to 4 bytes.
* Clang enforces this according to standard, GCC ignores it.
Use an additional alignas() specifier to let the compiler choose between
minimum alignment (packed) and "natural" alignment (non-packed). This is
both standard c++11 and compatible with older GCC, which does not
propagate alignment requirements of packed substructures properly.
* Assert alignment is suitable for atomic accesses
* Move fields and pad to meet alignment constraints
* Add padding to JackEngineControl to account for inherited data
* Parenthesise padding length for clarity
* Revert "Parenthesise padding length for clarity"
This reverts commit 1f757b9ece.
* Revert "Add padding to JackEngineControl to account for inherited data"
This reverts commit 3d8c7d83ad.
* Revert "Move fields and pad to meet alignment constraints"
This reverts commit ff631bbbdc.
* Assure alignment by using 'alignas' on fields