* Unaligned access support for pgm_read_word/dword
* Fix pgm_read_ptr_aligned() per #5735
* Allow users to use aligned-only via a #define
Adding -DPGM_READ_UNALIGNED=0 or #define PGM_READ_UNALIGNED 0 will
change the default at compile-time to only aligned (faster, but less
compatible) macro implementations.
Default is still to allow unaligned accesses.