Speedup localgraph (#1610)
Speedup localgraph (#1610)

* LocalGraph : Replace seen unordered_set by boolean check.

* LocalGraph : use unordered_map to store index -> last set_local instead of vector.

* LocalGraph :
 - Use internal counter to avoid invalidation at each cycle.
 - Move all blocks structs into a contiguous vector of smaller ones.

WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen