common: stub certain modules and functions on Windows

common: stub certain modules and functions on Windows

We're going to stub certain modules and functions for Windows builds.
Some of them will be implemented in subsequent commits, some are platform
specific and will be skipped.

Modules:
* module.c
* subprocess.cc
* blkdev.cc
* dns_resolve.cc
* numa.cc
* syslog.h
* statvfs.h
* libblk
* neorados

Functions:
x signal functions
x fork
x chown
* socketpair_cloexec
* dump_open_fds
* run_cmd
* is_symlink
* CInode::d_type
* nbd commands

Signed-off-by: Lucian Petrut <lpetrut@cloudbasesolutions.com>
Signed-off-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>