g_hash_table_new_full() had an invocation of
g_hash_table_realloc_key_or_value_array() with the @is_big argument
incorrectly hardcoded to FALSE, even though later in the function the
values of have_big_keys and have_big_values would be set conditionally.

This never caused problems before because on 64bit platforms, this would
result in the allocation of a guint-sized array (which would be fine, as
have_big_keys and have_big_values would always start out as false) and
on 32bit platforms, this function ignored the value and always allocated
a gpointer-sized array.

Since merge request !845 we have the possibility for
have_big_keys and have_big_values to start out as TRUE on 64bit
platforms.  We need to make sure we pass the argument through correctly.