patch 9.0.0930: cannot debug the Kitty keyboard protocol with TermDebug

Problem:    Cannot debug the Kitty keyboard protocol with TermDebug.
Solution:   Add Kitty keyboard protocol support to the libvterm fork.
            Recognize the escape sequences that the protocol generates.  Add
            the 'keyprotocol' option to allow the user to specify for which
            terminal what protocol is to be used, instead of hard-coding this.
            Add recognizing the kitty keyboard protocol status.
diff --git a/src/option.h b/src/option.h
index eed12e8..6f27013 100644
--- a/src/option.h
+++ b/src/option.h
@@ -698,6 +698,7 @@
 #endif
 EXTERN char_u	*p_kp;		// 'keywordprg'
 EXTERN char_u	*p_km;		// 'keymodel'
+EXTERN char_u	*p_kpc;		// 'keyprotocol'
 #ifdef FEAT_LANGMAP
 EXTERN char_u	*p_langmap;	// 'langmap'
 EXTERN int	p_lnr;		// 'langnoremap'