clang -O2  -Wall -Wextra -Werror=implicit-function-declaration fcntl/openat.c -o fcntl/openat -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
../out/minix/basic/fcntl/openat.o: In function `main':
fcntl/openat.c:(.text+0x30e): undefined reference to `openat'
fcntl/openat.c:(.text+0x32a): undefined reference to `openat'
clang: error: linker command failed with exit code 1 (use -v to see invocation)