I couldn't find an documented answer anywhere and I don't know how to code C nor the issue. The actual system is GNU Glibc. I am using GNU make. It compiles fine under Glibc but with musl-gcc I get this error:
a - libutil/strtonum.o
a - libutil/unescape.o
a - libutil/writeall.o
/usr/x86_64-pc-linux-gnu/binutils-bin/2.46.0/ld: libutil.a(recurse.o): in function `recurse':
recurse.c:(.text+0x59): undefined reference to `fstatat64'
/usr/x86_64-pc-linux-gnu/binutils-bin/2.46.0/ld: recurse.c:(.text+0x18f): undefined reference to `openat64'
/usr/x86_64-pc-linux-gnu/binutils-bin/2.46.0/ld: recurse.c:(.text+0x2ae): undefined reference to `readdir64'
/usr/x86_64-pc-linux-gnu/binutils-bin/2.46.0/ld: recurse.c:(.text+0x319): undefined reference to `fstatat64'
collect2: error: ld returned 1 exit status
make[1]: *** [Makefile:224: chgrp] Error 1
make: *** [Makefile:208: all] Error 2
$ grep CC config.mk
CC = /usr/local/musl/bin/musl-gcc
$ grep LDFLAGS config.mk
LDFLAGS = -static -no-pie
$ pwd
/mnt/lfs/usr/src/sbase
$ ls -ld /mnt/lfs/usr/src/
drwxrwxr-x 9 kevin kevin 4096 May 5 20:09 /mnt/lfs/usr/src/
$ findmnt -no OPTIONS /mnt/lfs
rw,nosuid,nodev,relatime