Enable stdlib hardening for libstdc++/libc++ #1464

Job	Run time
build-deb (debian:12)	4m 46s
build-deb (ubuntu:24.04)	5m 49s
build-flatpak	7m 6s
build-windows-mingw	7m 55s
build-deb (ubuntu:24.10)	5m 59s
build-rpm (fedora:40, gcc)	6m 1s
build-rpm (fedora:40, clang)	6m 30s
reuse-lint	16s
build-rpm (fedora:41, gcc)	5m 45s
build-rpm (fedora:41, clang)	7m 11s
build-rpm (opensuse/tumbleweed:latest, gcc)	6m 3s
build-macos / build-macos (arm64)	6m 49s
build-macos / build-macos (x86_64)	6m 17s
build-windows-msvc (msvc) / build-windows-msvc (amd64, x86_64)	1m 58s
build-windows-msvc (msvc) / build-windows-msvc (amd64_arm64, arm64)	2m 6s
build-windows-msvc (msvc-clang) / build-windows-msvc (amd64, x86_64)	52m 48s
build-windows-msvc (msvc-clang) / build-windows-msvc (amd64_arm64, arm64)	3m 35s
	2h 16m 54s

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