Fixes compilation with -save-temps flag (IDFGH-12615)

[denizzzka]

Project's root CMakeLists.txt:

cmake_minimum_required(VERSION 3.16)

# Preserve *.i files
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -save-temps")

include($ENV{IDF_PATH}/tools/cmake/project.cmake)
project(mcu_software)

If try to compile with -save-temps and with:

CONFIG_COMPILER_DISABLE_GCC12_WARNINGS=y
CONFIG_COMPILER_DISABLE_GCC13_WARNINGS=y

it causes error:
$ idf.py build lib
[...]
components/spiffs/spiffs/src/spiffs_nucleus.c: In function 'spiffs_populate_ix_map_v':
components/spiffs/spiffs/src/spiffs_nucleus.c:682:348: error: self-comparison always evaluates to false [-Werror=tautological-compare]

This PR fixes compilation for such case

Depends from #13612

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Note

Low Risk
CMake-only compile-flag wiring; no SPIFFS runtime or API behavior changes.

Overview
Fixes SPIFFS failing to compile when the project adds -save-temps to CMAKE_C_FLAGS and GCC 12/13 warning disables are not enabled globally (e.g. spiffs_populate_ix_map_v tripping -Werror=tautological-compare).

The component CMakeLists.txt now prepends ${CMAKE_CURRENT_LIST_DIR}/ to upstream SPIFFS sources before set_source_files_properties, so per-file flags like -Wno-format apply reliably with temp-file builds. It drops the old GNU-only -Wno-stringop-truncation block on spiffs_nucleus.c and instead appends -Wno-tautological-compare to that file’s existing compile flags (keeping -Wno-format).

^{Reviewed by Cursor Bugbot for commit 50f947e. Bugbot is set up for automated code reviews on this repo. Configure here.}

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[igrr]

@denizzzka Thanks for the PR, I think we can accept both changes in one branch (i.e. this PR). Could you please update the commit messages as suggested above by the checker, and click through the CLA?

[denizzzka]

Please pay attention to this PR

[denizzzka]

(still relevant)

[denizzzka]

Bump

@igrr

[igrr]

sha=41830433f4dc338b29ba1f97c5907bd805a271d8

[denizzzka]

Merging is blocked
You're not authorized to push to this branch. Visit https://docs.github.com/repositories/configuring-branches-and-merges-in-your-repository/managing-protected-branches/about-protected-branches for more information.

I don't understand what's going with this PR :-(

[denizzzka]

I don't understand. Why does the CI care about my local commit hooks?!

This tiny PR is already two years old, lol

[denizzzka]

Notice: It looks like the commits in this PR have been made without having pre-commit hooks installed.

This damn machine is lying!

Okay, just tell me if you need this or not. Maybe I'm wasting my time.

I hate your CI system.