clang linker error when compiling simple C program on OS X

Question

I was building this code from this article

I was using the recommended command to build it: gcc -Wall -o keyboard_leds keyboard_leds.c -framework IOKit -framework CoreFoundation

$ curl -O http://osxbook.com/book/bonus/chapter10/kbdleds/download/keyboard_leds.c
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 11542  100 11542    0     0   139k      0 --:--:-- --:--:-- --:--:--  140k

$ clang -Wall -o keyboard_leds keyboard_leds.c -framework IOKit -framework CoreFoundation
Undefined symbols for architecture x86_64:
  "_print_errmsg_if_err", referenced from:
      _create_hid_interface in keyboard_leds-d14ed5.o
  "_print_errmsg_if_io_err", referenced from:
      _create_hid_interface in keyboard_leds-d14ed5.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

$

The code is very straightforward, if a little dated (6 years). I cannot see any mention anywhere of the symbols that begin with the underscore. I'm probably missing something simple, but I'm completely stumped about where these symbols come from.

What gives? I can comment out the calls to get it to compile.