[m4] Add compatibility for GCC15 and use version ranges for all recipes in CCI

[uilianries]

Summary

Changes to recipe: m4/1.4.19

Motivation

fixes #29184

/cc @cuppajoeman

Details

When building M4 1.4.19 using GCC15, some errors can be found, like:

src/lib/gl_list.h:755:40: error: expected identifier or '(' before 'gl_list_node_t'
  755 | GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t

The full build log with several errors can be checked here: m4-1.4.19-linux-amd64-gcc15-release.log

Disabling warnings is not enough, as this error is related to the gnulib copied in m4, which does not support C23 (the default C and C++ standard for GCC15: https://gcc.gnu.org/gcc-15/changes.html#c). As a workaround, we keep C17 for GCC15 and it works just fine:

m4-1.4.19-linux-amd64-gcc15-cstd17-release.log

The case was officially reported before: https://savannah.gnu.org/support/?111150, and it was fixed in 1.4.20 as a new release gnulib was incorporated into the project: https://lists.gnu.org/archive/html/m4-announce/2025-05/msg00000.html. Bringing a new gnulib version as a backport is not viable, but the Buildroot project had a good insight by keeping C17 for compatibility: https://lists.buildroot.org/pipermail/buildroot/2025-May/777741.html

This bug is affecting only 1.4.19, the versions 1.4.18 and 1.4.20 can be built using GCC15 without errors:

• m4-1.4.18-linux-amd64-gcc15-release.log
• m4-1.4.20-linux-amd64-gcc15-release.log

To avoid future conflicts and to keep aligned with the latest version available, this PR also updates all recipes in ConanCenterIndex that are consuming the package for m4 to use version ranges.

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A second error appeared during the CI when building using Apple Clang 17, related to incompatible function pointer types:

• https://github.com/conan-io/conan-center-index/pull/29220/checks?check_run_id=58858365285
• https://github.com/conan-io/conan-center-index/pull/29220/checks?check_run_id=58868002204

As a workaround, I just passed -Wno-error=incompatible-pointer-types to ignore it for now.

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• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• If this is a bug fix, please link related issue or provide bug details
• Tested locally with at least one configuration using a recent version of Conan

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