[fix] remove breaking const qualifier on hints in configure

[antond-weta]

Description

The const qualifier on hints added in 215 breaks conversion. Rolling that change back.

Tests

Checklist:

• I have read the contribution guidelines.
• I have updated the documentation, if applicable. (Check if there is no
  need to update the documentation, for example if this is a bug fix that
  doesn't change the API.)
• I have ensured that the change is tested somewhere in the testsuite
  (adding new test cases if necessary).
• My code follows the prevailing code style of this project. If I haven't
  already run clang-format before submitting, I definitely will look at the CI
  test that runs clang-format and fix anything that it highlights as being
  nonconforming.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.42%. Comparing base (79c91eb) to head (c8e73a0).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #219      +/-   ##
==========================================
- Coverage   81.44%   81.42%   -0.02%     
==========================================
  Files          11       11              
  Lines        2150     2148       -2     
  Branches      325      325              
==========================================
- Hits         1751     1749       -2     
  Misses        399      399              

Files with missing lines	Coverage Δ
include/rawtoaces/image_converter.h	100.00% <ø> (ø)
src/rawtoaces_util/image_converter.cpp	71.49% <ø> (-0.06%)	⬇️

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[soswow]

I usually prefer to have regression test to accompony the revert/bug-fix. But it's ok to merge first and think of testing later.