v128.store8_lane() etc are improperly declared.

[petercockerell-brt]

Bug description

I'm trying to compile some code that uses v128.store8_lane():

      v128.store8_lane(i, v, 0, CHANNEL_R);

But I get the following compiler error:

[wasm-validator error in function src/assembly/wasm-util/wBayerToImageData] unexpected false: can only drop a valid value, on 
(drop
 (v128.store8_lane 0
  (local.get $35)
  (local.get $38)
 )
)

This seems to be because the declaration of the function is:

  export function store8_lane(ptr: usize, vec: v128, idx: u8, immOffset?: usize, immAlign?: usize): v128;

implying that it returns a value. However, the specification at https://github.com/WebAssembly/simd/blob/main/proposals/simd/SIMD.md implies there is no result left on the stack after one of these instructions, so the drop() is unnecessary.

Steps to reproduce

Compile an AssemblyScript function that uses the v128.store8_lane() function.

AssemblyScript version

0.27.4