cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/getentropy.c -o unistd/getentropy -D_POSIX_C_SOURCE=202405L  -lm -lpthread  -liconv
unistd/getentropy.c:5:30: error: use of undeclared identifier 'getentropy'
    5 | int (*foo)(void *, size_t) = getentropy;
      |                              ^
1 error generated.