remove xns support.  xns is not used any longer

Reference: /n/atom/patch/applied2013/noxns
Date: Thu Jun 13 05:25:29 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/port/mkdevc	Thu Jun 13 05:25:09 2013
+++ /sys/src/9/port/mkdevc	Thu Jun 13 05:25:10 2013
@@ -58,15 +58,12 @@
 		}
 	}
 }
-collect && section == "xns"{
-	xns[nxns++] = $1
-}
 collect && section == "port"{
 	sub(/^[ \t]*/, "");
 	port[nport++] = $0;
 }
 $0 ~ /^[^ \t]/{
-	if($0 ~ "(bootdir|dev|ip|xns|link|misc|port)"){
+	if($0 ~ "(bootdir|dev|ip|link|misc|port)"){
 		section = $0;
 		collect = 1;
 	}
@@ -177,16 +174,6 @@
 		printf "void (*ipprotoinit[])(Fs*) = {\n";
 		for(i = 0; i < nip; i++)
 			printf "\t%sinit,\n", ip[i];
-		printf "\tnil,\n};\n\n";
-	}
-
-	if(nxns){
-		printf "#include \"../xns/xns.h\"\n";
-		for(i = 0; i < nxns; i++)
-			printf "extern void %sinit(Xfs*);\n", xns[i];
-		printf "void (*xprotoinit[])(Xfs*) = {\n";
-		for(i = 0; i < nxns; i++)
-			printf "\t%sinit,\n", xns[i];
 		printf "\tnil,\n};\n\n";
 	}