Don't define ctrl key enums if already defined (e.g. in uifc.h).

src/xpdev/gen_defs.h

@@ -74,6 +74,7 @@
 #define LF		'\n'				/* Line feed				^J	*/
 #define CR		'\r'				/* Carriage return			^M	*/
 
+#if !CTRL_A
 enum {
 	 CTRL_A=1
 	,CTRL_B
@@ -102,6 +103,7 @@ enum {
 	,CTRL_Y
 	,CTRL_Z
 };
+#endif
 
 /* Unsigned type short-hands	*/
 #ifndef uchar