sam: clean up checkerrs (Rob Pike)

src/cmd/sam/shell.c

diff --git a/src/cmd/sam/shell.c b/src/cmd/sam/shell.c
index 8034893..32e1b3d 100644
--- a/src/cmd/sam/shell.c
+++ b/src/cmd/sam/shell.c
@@ -142,13 +142,13 @@
 void
 checkerrs(void)
 {
-	char buf[4096];
+	char buf[BLOCKSIZE-10];
 	int f, n, nl;
 	char *p;
 	long l;
 
 	if(statfile(errfile, 0, 0, 0, &l, 0) > 0 && l != 0){
-		if((f=open((char *)errfile, 0)) != -1){
+		if((f=open(errfile, 0)) != -1){
 			if((n=read(f, buf, sizeof buf-1)) > 0){
 				for(nl=0,p=buf; nl<25 && p<&buf[n]; p++)
 					if(*p=='\n')
@@ -161,5 +161,5 @@
 			close(f);
 		}
 	}else
-		remove((char *)errfile);
+		remove(errfile);
 }