Fix the missing `STATIC` modfier of static phantom fields in `ClassHierarchyImpl`

[jjppp]

This PR should fix #169, where the modifier STATIC is missing for static phantom fields, making subsequent analysis mistakenly considering static phantom fields to be instance fields.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 72.86%. Comparing base (6774a9f) to head (34d7897).

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Additional details and impacted files

@@             Coverage Diff              @@
##             master     #170      +/-   ##
============================================
+ Coverage     72.79%   72.86%   +0.06%     
- Complexity     4431     4436       +5     
============================================
  Files           480      480              
  Lines         15922    15925       +3     
  Branches       2183     2184       +1     
============================================
+ Hits          11591    11603      +12     
+ Misses         3479     3468      -11     
- Partials        852      854       +2     

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