patch 8.1.0069: cannot handle pressing CTRL-C in a prompt buffer

Problem:    Cannot handle pressing CTRL-C in a prompt buffer.
Solution:   Add prompt_setinterrupt().
diff --git a/src/edit.c b/src/edit.c
index 3204ec3..6a636b9 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -1016,6 +1016,19 @@
 		goto doESCkey;
 	    }
 #endif
+#ifdef FEAT_JOB_CHANNEL
+	    if (c == Ctrl_C && bt_prompt(curbuf))
+	    {
+		if (invoke_prompt_interrupt())
+		{
+		    if (!bt_prompt(curbuf))
+			// buffer changed to a non-prompt buffer, get out of
+			// Insert mode
+			goto doESCkey;
+		    break;
+		}
+	    }
+#endif
 
 #ifdef UNIX
 do_intr: