Remove type quad, use type word_t in PowerPC as.

Remove type quad, use type word_t in PowerPC as.

Type word_t is for encoding the machine instructions.  It only needs
32 bits for PowerPC.  It was long (which can have 32 or 64 bits), and
there was a second type quad (which was uint32_t).  Switch word_t to
uint32_t and replace quad with word_t.

Also change valu_t and ADDR_T away from long.