patch 8.1.2145: cannot map <C-H> when modifyOtherKeys is enabled

Problem:    Cannot map <C-H> when modifyOtherKeys is enabled.
Solution:   Add the <C-H> mapping twice, both with modifier and as 0x08.  Use
            only the first one when modifyOtherKeys has been detected.
diff --git a/src/globals.h b/src/globals.h
index d790c82..014fca2 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1002,6 +1002,10 @@
 EXTERN int reg_recording INIT(= 0);	// register for recording  or zero
 EXTERN int reg_executing INIT(= 0);	// register being executed or zero
 
+// Set when a modifyOtherKeys sequence was seen, then simplified mappings will
+// no longer be used.
+EXTERN int seenModifyOtherKeys INIT(= FALSE);
+
 EXTERN int no_mapping INIT(= FALSE);	// currently no mapping allowed
 EXTERN int no_zero_mapping INIT(= 0);	// mapping zero not allowed
 EXTERN int allow_keys INIT(= FALSE);	// allow key codes when no_mapping