fix enum-range check for LHSs

[kroening]

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

Attention: Patch coverage is 82.75862% with 5 lines in your changes missing coverage. Please review.

Project coverage is 78.38%. Comparing base (b71084c) to head (53454fd).
Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/ansi-c/goto-conversion/goto_check_c.cpp	82.75%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8544      +/-   ##
===========================================
- Coverage    78.55%   78.38%   -0.18%     
===========================================
  Files         1729     1729              
  Lines       199722   200151     +429     
  Branches     18312    18244      -68     
===========================================
- Hits        156888   156883       -5     
- Misses       42834    43268     +434     

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