ioemu: config cleanup re AF_UNIX sockets on non-Windows

ioemu: config cleanup re AF_UNIX sockets on non-Windows

Here is what I wrote in my submission to qemu upstream:

 The patch below makes it possible to disable AF_UNIX (unix-domain)
 sockets in host environments which do not define _WIN32, by adding
 -DNO_UNIX_SOCKETS to the compiler flags.  This is useful in the
 effectively-embedded qemu host which are going to be using for device
 emulation in Xen.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>