Definition of wasm_functype_new_x_y helpers - use of a macro prevents coding errors when extending.

[adv-sw]

Suggest macro helper in the intializer as follows to make it even easier :)

#define ARRAY_LENGTH(x) sizeof(x)/sizeof(x[0])

static inline wasm_functype_t* wasm_functype_new_5_1(wasm_valtype_t* p1, wasm_valtype_t* p2, wasm_valtype_t* p3, wasm_valtype_t* p4, wasm_valtype_t* p5, wasm_valtype_t* r)
{
wasm_valtype_t* ps[5] = {p1, p2, p3, p4, p5};
wasm_valtype_t* rs[1] = {r};
wasm_valtype_vec_t params, results;
wasm_valtype_vec_new(&params, ARRAY_LENGTH(ps), ps);
wasm_valtype_vec_new(&results, ARRAY_LENGTH(rs), rs);
....

[rossberg]

I believe this is implemented/superseded by #145.