bug#1483: cleanup: replace NO_SOCKETS_IN_FILE_SYSTEM in emacsclient.c

[jasonr]

Quoting Dan Nicolaescu <dann@ics.uci.edu>:

> NO_SOCKETS_IN_FILE_SYSTEM is the same as WINDOWSNT, so better replace it
> and have one less identifier to worry about.

Does DOS have unix domain sockets?

And what happens when someone adds emulation of them for WINDOWSNT, they need to
go through every WINDOWSNT define to figure out which are dealing with this
feature?

In general conditional compilation should deal with features, not platforms,
even if only one platform is missing that feature.

PS: Why are you reporting this as a bug?