to a buffer in the big key/data case, memmove() was used on pointers
to size_ts, but only sizeof(u_int32_t) bytes where copied. This broke
on big_endian architectures where sizeof(size_t) > sizeof(u_int32_t).
This bug broke portupgrade (by way of ruby_bdb1) on sparc64.
Approved by: re (rwatson)