Fix #79311: enchant_dict_suggest() fails on big endian architecture

Fix #79311: enchant_dict_suggest() fails on big endian architecture

For obvious reasons, we must not assign a `size_t` value to an `int`
variable using memcpy().  However, there is actually no need for the
intermediate `n_sugg_st` here, if we use the proper types in the first
place.

A regression test is not necessary, because dict_suggest.phpt already
exhibits the erroneous behavior on big endian architectures.