eet_data: guarantee double-word alignment for temporary stack buffer.

eet_data: guarantee double-word alignment for temporary stack buffer.

The code was giving enough memory to store doubles and longs, but they
could be unaligned as "unsigned char" allows 1-byte alignment, while
double may require 8 bytes.

By specifying the array as "long long" we force certain alignment in a
platform independent way. As this array is small enough and
short-lived, the number of items were not changed, this results in
more bytes on the stack but it shouldn't matter.