acme: win(1) doesn't handle the new MR/Mr events (shift-clicks)

[mbivert]

0c79c32 recently added new MR/Mr events to trigger backward search on shift-click; those events aren't handled in src/cmd/9term/win.c:

unknown message MR
unknown message MR

Forwarding them essentially (acme(4) doesn't mention the use of a flag for R/r) as we do for ML/Ml seems to do the job:

% git diff win.c
diff --git a/src/cmd/9term/win.c b/src/cmd/9term/win.c
index 9c7a12eb..c2e58086 100644
--- a/src/cmd/9term/win.c
+++ b/src/cmd/9term/win.c
@@ -464,6 +464,9 @@ stdinproc(void *v)
 				/* just send it back */
 				if(e.flag & 2)
 					gete(efd, &e2);
+				// fallthrough
+			case 'r':
+			case 'R':
 				fsfidprint(efd, "%c%c%d %d\n", e.c1, e.c2, e.q0, e.q1);
 				break;