In e.g. Linux users can set CPATH and LIBRARY_PATH to a list of paths considered by e.g. GCC, Clang, ... as if they were passed to `-I`, `-L`

These paths show up in the verbose compiler output too.

However in native builds (not cross-compiling) these variables/directories are ignored which leads to failure of e.g. building the BZip2 extension (among others).

Use case: On HPC modules are used, which means e.g. BZip2 is not installed into a system directory but into some other folder and CPATH, LIBRARY_PATH, LD_LIBRARY_PATH, ... are modified so it can be found by compiler and runtime. However the Python build script does not find it as it ignores those "compiler paths".

This did work ages ago, but was broken when it was decided that compiler paths (output of `gcc -E -v`) is no longer used for native builds and that function was later even renamed: https://github.com/python/cpython/commit/32f5fdd7f4213743fe2f6eedd0fe2108f3157021#diff-2eeaed663bd0d25b7e608891384b7298R514

I propose to rename the function back to its original name and use it always.