Fix integer overflow in layer_resize in map_engine.c (#268)

* Fix integer overflow in layer_resize in map_engine.c

There's a buffer overflow bug in the function layer_resize. It allocates
a buffer `tilemap` with size `x_size * y_size * sizeof(struct map_tile)`.
But it didn't check for integer overflow, so if x_size and y_size are
very large, it's possible that the buffer size is smaller than needed,
causing a buffer overflow later.

PoC: `SetLayerSize(0, 0x7FFFFFFF, 0x7FFFFFFF);`

* move malloc to a separate line
person_get_ignore_tiles(const person_t* person)
{
	return person->ignore_all_tiles;
}

person_get_ignore_tiles(const person_t* person)
{
	return person->ignore_all_tiles;
}
