Remove the last traces of the no longer existing cmd_l command

cmd_l was still mentioned in the documentation and comments. Also,
there was no test for the "v" command which would test #18900.

Author: choroba

lib/perl5db.pl

@@ -2544,7 +2544,7 @@ sub _DB__handle_i_command {
     next CMD;
 }
 
-=head3 C<cmd_l> - list lines (command)
+=head3 C<_cmd_l_main> - list lines (command)
 
 Most of the command is taken up with transforming all the different line
 specification syntaxes into 'start-stop'. After that is done, the command
@@ -6001,7 +6001,7 @@ sub cmd_O {
 =head3 C<cmd_v> - view window (command)
 
 Uses the C<$preview> variable set in the second C<BEGIN> block (q.v.) to
-move back a few lines to list the selected line in context. Uses C<cmd_l>
+move back a few lines to list the selected line in context. Uses C<_cmd_l_main>
 to do the actual listing after figuring out the range of line to request.
 
 =cut
@@ -6027,7 +6027,7 @@ sub cmd_v {
         # Back up by the context amount.
         $start -= $preview;
 
-        # Put together a linespec that cmd_l will like.
+        # Put together a linespec that _cmd_l_main will like.
         $line = $start . '-' . ( $start + $incr );
 
         # List the lines.

lib/perl5db.t

@@ -3051,6 +3051,25 @@ SKIP:
        );
 }
 
+{
+    # gh #19170
+    my $wrapper = DebugWrap->new(
+        {
+            cmds =>
+            [
+                'v',
+                'q',
+            ],
+            prog => '-e1',
+        }
+    );
+
+    $wrapper->contents_like(
+        qr/1==>\t1\n/,
+        q/v works/,
+       );
+}
+
 SKIP:
 {
     $Config{usethreads}