fix little bits left behind from original patch.

Reference: /n/atom/patch/applied2013/bootlocal2
Date: Fri Oct 11 21:00:05 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/boot/local.c	Fri Oct 11 20:59:53 2013
+++ /sys/src/9/boot/local.c	Fri Oct 11 20:59:53 2013
@@ -9,16 +9,13 @@
 void
 configlocal(Method *mp)
 {
-	char *p;
-	int n;
-
 	if(*sys == '/' || *sys == '#'){
 		/*
 		 *  if the user specifies the disk in the boot cmd or
 		 * 'root is from' prompt, use it
 		 */
 		disk = sys;
-	} else if(mp->arg){
+	} else if(mp->arg != nil){
 		/*
 		 *  a default is supplied when the kernel is made
 		 */
@@ -33,7 +30,7 @@
 	}
 
 	/* if we've decided on one, pass it on to all programs */
-	if(disk)
+	if(disk != nil)
 		setenv("bootdisk", disk);
 
 	USED(mp);
--- /sys/src/nix/boot/local.c	Fri Oct 11 20:59:53 2013
+++ /sys/src/nix/boot/local.c	Fri Oct 11 20:59:53 2013
@@ -9,16 +9,13 @@
 void
 configlocal(Method *mp)
 {
-	char *p;
-	int n;
-
 	if(*sys == '/' || *sys == '#'){
 		/*
 		 *  if the user specifies the disk in the boot cmd or
 		 * 'root is from' prompt, use it
 		 */
 		disk = sys;
-	} else if(mp->arg){
+	} else if(mp->arg != nil){
 		/*
 		 *  a default is supplied when the kernel is made
 		 */
@@ -33,7 +30,7 @@
 	}
 
 	/* if we've decided on one, pass it on to all programs */
-	if(disk)
+	if(disk != nil)
 		setenv("bootdisk", disk);
 
 	USED(mp);