unimplemented symbolic instructions

[zapashcanon]

• memory.fill
• memory.blit
• i32.popcnt, i64.popcnt
• trunc_sat_f{32,64}_{s,u}

[zapashcanon]

@filipeom, do you know how hard it'll be to have the popcnt and trunc_sat in smtml ?

Also, do you think we can get memory.blit and memory.fill at some point (with the new memory model) ?

[filipeom]

For popcnt I can add some dumb function to calculate it now.

For memory.blit and memory.fill these should work well with the new memory model 😄