This fixes the following compile errors with uClibc:

lxc_snapshot.c: In function 'print_file':
lxc_snapshot.c:71:2: error: implicit declaration of function 'getline' [-Werror=implicit-function-declaration]
  while (getline(&line, &sz, f) != -1) {
  ^
cc1: all warnings being treated as errors

lxc_usernsexec.c: In function 'read_default_map':
lxc_usernsexec.c:181:2: error: implicit declaration of function 'getline' [-Werror=implicit-function-declaration]
  while (getline(&line, &sz, fin) != -1) {
  ^
cc1: all warnings being treated as errors
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>