Allow OPENSSL_NO_SOCK in e_os.h even for non-Windows/DOS platforms

UEFI needs this too. Don't keep it only in the Windows/DOS ifdef block.

This is a fixed version of what was originally commit 963bb621 and
subsequently reverted in commit 37b1f8bd

. Somewhere along the way, the
Windows/DOS ifdef actually got removed, leaving it just broken. It should
have been turned into an #elif, not removed.

This one correctly changes the logic from

    # if WINDOWS|DOS
    #  if OPENSSL_NO_SOCK
        ... no-sock ...
    #  elif !DJGPP
        ... native windows ...

to

    # if OPENSSL_NO_SOCK
       ... no-sock ...
    # elif WINDOWS|DOS
    #  if !DJGPP
        ... native windows ...

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>