[9front] cmd/sort: fix resource leak (patch)

["Igor Boehm" <boehm.igor@gmail.com>]

There is a small resource leak in cmd/sort.c:/^dofile.

Here is the code with some hopefully explanatory annotations (one
liner patch is below):

<snip>
void
dofile(Biobuf *b)
{
	Line *l, *ol;
	int n;

	if(args.cflag) {
		if((ol = newline(b)) == nil)
			return;
		for(;;) {
			if((l = newline(b)) == nil)
				break;
^^^^^^^^^^^^^^^^^^^^^^
Break out of for leakes 'ol' 				
				
			n = kcmp(ol->key, l->key);
			if(n > 0 || (n == 0 && args.uflag)) {
				fprint(2, "sort: -c file not in sort\n"); /**/
				done("order");
			}
			free(ol->key);
			free(ol);
			ol = l;
^^^^^^^^^^^^^^^^^^^^^^
Assign 'l' to 'ol' and again break out of for would leak that		
		}
		return;
^^^^^^^^^^^^^^^
There should be a 'free(ol);' before this 'return'
	}
</snip>

Here is the one line fix as an inline diff:

diff -r 4c6206d69abb sys/src/cmd/sort.c
--- a/sys/src/cmd/sort.c	Mon Dec 28 21:21:22 2020 +0100
+++ b/sys/src/cmd/sort.c	Tue Dec 29 15:11:29 2020 +0100
@@ -209,6 +209,7 @@
 			free(ol);
 			ol = l;
 		}
+		free(ol);
 		return;
 	}