Fix recording "too many" returns

[phipsgabler]

Currently, every return statement is always recorded, even if there actually happend a jump before it; see both @7s here:

@1: [Argument §1:%1] = Main.DynamicComputationGraphs.weird
@2: [Argument §1:%2] = 3
@3: [§1:%3] Main.DynamicComputationGraphs.rand() = 0.666241398790441
  @1: [Argument §1:%1] = rand
  @2: [§1:%2] (@1)(Random.GLOBAL_RNG, Random.Float64) = 0.666241398790441
  @3: [§1:1] return @2 = 0.666241398790441
@4: [§1:%4] @2 + 1 = 4
  @1: [Argument §1:%1] = +
  @2: [Argument §1:%2] = 3
  @3: [Argument §1:%3] = 1
  @4: [§1:%4] Base.add_int(@2, @3) = 4
  @5: [§1:1] return @4 = 4
@5: [§1:%5] 1 / @4 = 0.25
  @1: [Argument §1:%1] = /
  @2: [Argument §1:%2] = 1
  @3: [Argument §1:%3] = 4
  @4: [§1:%4] Base.float(@2) = 1.0
  @5: [§1:%5] Base.float(@3) = 4.0
  @6: [§1:%6] @4 / @5 = 0.25
  @7: [§1:1] return @6 = 0.25
@6: [§1:%6] @3 < @5 = false
  @1: [Argument §1:%1] = <
  @2: [Argument §1:%2] = 0.666241398790441
  @3: [Argument §1:%3] = 0.25
  @4: [§1:%4] Base.lt_float(@2, @3) = false
  @5: [§1:1] return @4 = false
@7: [§1:2] return @2 = 3
@8: [§1:1] goto §2 since @6
@9: [§2:%7] @2 + 1 = 4
  @1: [Argument §1:%1] = +
  @2: [Argument §1:%2] = 3
  @3: [Argument §1:%3] = 1
  @4: [§1:%4] Base.add_int(@2, @3) = 4
  @5: [§1:1] return @4 = 4
@10: [§2:%8] Main.DynamicComputationGraphs.weird(@9) = 12
  @1: [Argument §1:%1] = Main.DynamicComputationGraphs.weird
  @2: [Argument §1:%2] = 4
  @3: [§1:%3] Main.DynamicComputationGraphs.rand() = 0.2498905338845061
  @4: [§1:%4] @2 + 1 = 5
  @5: [§1:%5] 1 / @4 = 0.2
  @6: [§1:%6] @3 < @5 = false
  @7: [§1:2] return @2 = 4
  @8: [§1:1] goto §2 since @6
  @9: [§2:%7] @2 + 1 = 5
  @10: [§2:%8] Main.DynamicComputationGraphs.weird(@9) = 12
  @11: [§2:1] return @10 = 12
@11: [§2:1] return @10 = 12% 

This was something I didn't think of before. Solution: replace the return-recording by a branch to a new, last block, which does the recording and takes the Return as an argument, just as with Branches.

(This is not an "error", it just does unnecessary things and shifts the tapes indices).

[phipsgabler]

Fixed by 5152878.