diff: clean up some comments

I did the tidying and fixes. Let's remove those
comments.

sys/src/cmd/diff/diffio.c

@@ -141,8 +141,8 @@ prepare(int i, char *arg, char *orig)
 		p = erealloc(p, (++j+3)*sizeof(Line));
 	len[i] = j;
 	file[i] = p;
-	input[i] = bp;			/*fix*/
-	if (i == 0) {			/*fix*/
+	input[i] = bp;
+	if (i == 0) {
 		file1 = orig;
 		firstchange = 0;
 	} else

sys/src/cmd/diff/diffreg.c

@@ -89,7 +89,6 @@ int clen;
 int *J;		/*will be overlaid on class*/
 long *ixold;	/*will be overlaid on klist*/
 long *ixnew;	/*will be overlaid on file[1]*/
-/* END OF SOME TIDYING */
 
 static void	
 sort(Line *a, int n)	/*shellsort CACM #201*/