patch 9.0.0939: still using simplified mappings when using kitty protocol

Problem:    Still using simplified mappings when using the kitty keyboard
            protocol.
Solution:   Use the kitty_protocol_state value to decide whether to use
            simplified mappings.  Improve how seenModifyOtherKeys is set and
            reset.
diff --git a/src/structs.h b/src/structs.h
index 1a7a46c..111872d 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1264,7 +1264,7 @@
     int		m_keylen;	// strlen(m_keys)
     int		m_mode;		// valid mode
     int		m_simplified;	// m_keys was simplified, do not use this map
-				// if seenModifyOtherKeys is TRUE
+				// if key_protocol_enabled() returns TRUE
     int		m_noremap;	// if non-zero no re-mapping for m_str
     char	m_silent;	// <silent> used, don't echo commands
     char	m_nowait;	// <nowait> used