Build with PGO needlesly generates JIT stencils twice (and prevents usage of prebuilt stencils)

[hroncok]

Bug report

Bug description:

Based on https://discuss.python.org/t/building-the-jit-with-pre-built-stencils/91838/12 I open this issue to have an issue number to reference in an upcoming PR.

When a build with PGO optimizations is used, the JIT stencils are generated, then deleted, and then generated again. The generated JIT stencils are bit-by-bit identical to each other, so I believe there is no need to delete them mid-build. Not deleting them is also a prerequisite for Fedora to be able to use pre-built JIT stencils on platforms without the required LLVM version.

CPython versions tested on:

3.15, CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-141808: Don't remove the JIT stencils when building with PGO #141809
• GH-141808: Do not generate the jit stencils twice in case of PGO builds on Windows. #142043
• [3.14] GH-141808: Do not generate the jit stencils twice in case of PGO builds on Windows. (GH-142043) #142100

[hroncok]

I am testing if I can move the removal from make clean-retain-profile to make clean.

EDIT: That's not enough.

[chris-eibl]

Like written in https://discuss.python.org/t/building-the-jit-with-pre-built-stencils/91838/14, this happens on Windows, too.
The fix is IMHO simple, see #142043.