Fix compile on Alpine Linux

When compiling vzctl on Alpine Linux 3.3.1, there is a number of errors
like these:

hooks_vz.c:513:11: error: 'PATH_MAX' undeclared (first use in this function)
hooks_vz.c:600:11: error: 'PIPE_BUF' undeclared (first use in this function)

Fix by adding #include <limits.h>

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
2 files changed