Fix regression on reconfigure with unnormalized -DCMAKE_<LANG>_COMPILER=

Since commit 3f2a5971c0 (Modules: CMAKE_*_COMPILER convert path to cmake
path, 2023-12-02, v3.29.0-rc1~292^2) we normalize the path to the
compiler.  Update our logic that checks whether the compiler has changed
to account for path normalization.

Fixes: #25883
Issue: #25456