Sync top-level with GCC

Sync top-level with GCC

This just brings in the following two changes:

commit 04df8fa9e73e612f978fff35a97841703b872f6c
Author:     Thomas Schwinge <tschwinge@baylibre.com>
AuthorDate: Tue Oct 21 09:46:32 2025 +0200
Commit:     Thomas Schwinge <tschwinge@baylibre.com>
CommitDate: Fri Oct 24 12:40:22 2025 +0200

    Simplify 'Makefile' dependencies for libatomic [PR81358]

    ...

commit e63cf4b130b86dd7dde1bf499d3d40faca10ea2e
Author:     Prathamesh Kulkarni <prathameshk@nvidia.com>
AuthorDate: Thu Oct 9 07:07:24 2025 +0000
Commit:     Prathamesh Kulkarni <prathameshk@nvidia.com>
CommitDate: Thu Oct 9 07:26:51 2025 +0000

    PR81358: Enable automatic linking of libatomic.

    ...

ChangeLog:

	* Makefile.def: Sync with GCC.
	* configure.ac: Ditto.
	* configure: Regenerate.