This is especially necessary since GCC 16.x.
=====
$ gcc --version
gcc (GCC) 16.2.1 20260819 (Red Hat 16.2.1-2)
Copyright (C) 2026 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
=====
Without this change, /usr/include/limits.h is not included, hence POSIX
constants are not defined:
=====
$ echo '#include <limits.h>' | gcc -E -H -isystem ~/git/systemd/src/include/musl - 2>&1 >/dev/null | grep '^\..*limit'
. /home/watanabe/git/systemd/src/include/musl/limits.h
.. /usr/lib/gcc/x86_64-redhat-linux/16/include/limits.h
... /usr/lib/gcc/x86_64-redhat-linux/16/include/syslimits.h
=====
With this change, /usr/include/limits.h is included, thus POSIX
constants are defined:
=====
$ echo '#include <limits.h>' | gcc -E -H -isystem ~/git/systemd/src/include/musl - 2>&1 >/dev/null | grep '^\..*limit'
. /home/watanabe/git/systemd/src/include/musl/limits.h
.. /usr/lib/gcc/x86_64-redhat-linux/16/include/limits.h
... /usr/include/limits.h
...... /usr/include/linux/limits.h
.. /usr/lib/gcc/x86_64-redhat-linux/16/include/limits.h
=====
Replaces #43824.
Yu Watanabe
6a131b32e0