Reevaluate debug sequence points after shortening jumps

[Slava0135]

Problem

Debug sequence points offsets were not updated after removing NOP during jump shortening

Solution

Count NOPs before seqpoint and offset opcodes on this amount
Added tests to check that reevaluation was correct

[Slava0135]

question: should debug points be removed if they were replaced with NOP, panic or keep code as is?

[roman-khimov]

should debug points be removed if they were replaced with NOP

Likely we'll just have several points at the same offset and then hi, #2428.

[AnnaShaleva]

Could you, please, squash the commits and add signoff-by to the commit message?

The fix itself looks legit, let me test it a bit.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.17%. Comparing base (fb4a4f0) to head (9b688a9).
Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3412      +/-   ##
==========================================
+ Coverage   86.10%   86.17%   +0.06%     
==========================================
  Files         331      331              
  Lines       38107    38114       +7     
==========================================
+ Hits        32813    32845      +32     
+ Misses       3780     3751      -29     
- Partials     1514     1518       +4     

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[AnnaShaleva]

Also please, add compiler: prefix to the commit message. Like the following: compiler: reevaluate debug sequence points after shortening jumps. Ref. https://github.com/nspcc-dev/.github/blob/master/git.md#commit-messages.

[AnnaShaleva]

@roman-khimov, agree to merge?

[roman-khimov]

Seems to be a nice fix.