Support for SOCKS wrappers in Unix.i3.

Index: m3/m3core/src/unix/freebsd-2/Unix.i3
--- Unix.i3.orig	Sat Jan  7 14:41:42 1995
+++ Unix.i3	Tue Oct  8 14:20:50 1996
@@ -94,7 +94,7 @@
 (* ok *)
 
 (*** close - delete a descriptor ***)
-<*EXTERNAL*> PROCEDURE close (d: int): int;
+<*EXTERNAL "m3_close"*> PROCEDURE close (d: int): int;
 (* ok *)
 
 (*** creat - create a new file ***)
@@ -102,8 +102,8 @@
 (* ok, but obsolete *)
 
 (*** dup, dup2 - duplicate an open file descriptor ***)
-<*EXTERNAL*> PROCEDURE dup (oldd: int): int;
-<*EXTERNAL*> PROCEDURE dup2 (oldd, newd: int): int;
+<*EXTERNAL "m3_dup"*> PROCEDURE dup (oldd: int): int;
+<*EXTERNAL "m3_dup2"*> PROCEDURE dup2 (oldd, newd: int): int;
 (* ok *)
 
 (*** execve - execute a file ***)
@@ -892,7 +892,7 @@
 TYPE
   FDSet = SET OF [0 .. MAX_FDSET - 1];
 
-<*EXTERNAL*> PROCEDURE select (nfds: int;
+<*EXTERNAL "m3_select"*> PROCEDURE select (nfds: int;
                            readfds, writefds, exceptfds: UNTRACED REF FDSet;
                            timeout: UNTRACED REF struct_timeval): int;
 (* ok *)