bench: indirect call benchmark

[axic]

It gets inefficiently compiled to exactly what we want to test:

  (func $fnv1 (type $t0) (param $p0 i64) (param $p1 i64) (result i64)
    get_local $p1
    get_local $p0
    i64.xor
    i64.const 1099511628211
    i64.mul)
  (func $threeab (type $t0) (param $p0 i64) (param $p1 i64) (result i64)
    get_local $p0
    i64.const 3
    i64.mul
    get_local $p1
    i64.add)
  (func $icall (export "icall") (type $t2) (param $p0 i32) (result i32)
    (local $l0 i64) (local $l1 i32)
    block $B0
      get_local $p0
      i32.eqz
      br_if $B0
      i64.const -3750763034362895579
      set_local $l0
      i32.const 0
      set_local $l1
      loop $L1
        get_local $l0
        i64.const 1311768467294899695
        get_local $l1
        i32.const 1
        i32.and
        i32.const 2
        i32.shl
        i32.const 1024
        i32.add
        i32.load
        call_indirect (type $t0)
        set_local $l0
        get_local $p0
        get_local $l1
        i32.const 1
        i32.add
        tee_local $l1
        i32.ne
        br_if $L1
      end
      get_local $l0
      i32.wrap/i64
      return
    end
    i32.const -2078137563)

[axic]

Quick run:
master:

fizzy/execute/micro/icall_hash/1000_steps         335 us          330 us         2255
 wabt/execute/micro/icall_hash/1000_steps         356 us          353 us         2015
wasm3/execute/micro/icall_hash/1000_steps        37.9 us         37.6 us        18619

#616:

fizzy/execute/micro/icall_hash/1000_steps         131 us          121 us         5731
 wabt/execute/micro/icall_hash/1000_steps         342 us          340 us         2080
wasm3/execute/micro/icall_hash/1000_steps        38.2 us         37.6 us        19328

[codecov]

Codecov Report

Merging #632 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #632   +/-   ##
=======================================
  Coverage   98.33%   98.33%           
=======================================
  Files          67       67           
  Lines        9535     9535           
=======================================
  Hits         9376     9376           
  Misses        159      159