fix[lang]: fix panic in call cycle detection

[cyberthirst]

What I did

• fix: panic on some cyclic function call checks #4194

How I did it

• check if the func called is the func itself

How to verify it

• added test

Commit Message

fix cycle detection in `_compute_reachable_set()` by adding a check for
subcycles in the current call path

the function was detecting cycles by checking for a cyclic call to the
*root* of the call path

if the cycle was within the call path (excluding the root) it could
fall into infinite recursion

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 46.14%. Comparing base (99304da) to head (4e44664).

Files	Patch %	Lines
vyper/semantics/analysis/module.py	0.00%	3 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (99304da) and HEAD (4e44664). Click for more details.

HEAD has 139 uploads less than BASE

Flag	BASE (99304da)	HEAD (4e44664)
	140	1

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4200       +/-   ##
===========================================
- Coverage   91.36%   46.14%   -45.23%     
===========================================
  Files         109      109               
  Lines       15614    15617        +3     
  Branches     3436     3437        +1     
===========================================
- Hits        14266     7206     -7060     
- Misses        919     7856     +6937     
- Partials      429      555      +126     

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[charles-cooper]

nice, very clean!