variable.h, reduce visibility of auxiliary struct xxx to variable.c

src/frontend/variable.c

@@ -882,6 +882,12 @@ vareval(char *string)
 }
 
 
+struct xxx {
+    struct variable *x_v;
+    char x_char;
+};
+
+
 static int
 vcmp(const void *a, const void *b)
 {

src/frontend/variable.h

@@ -29,11 +29,6 @@ struct variable {
 #define va_string va_V.vV_string
 #define va_vlist  va_V.vV_list
 
-struct xxx {
-    struct variable *x_v;
-    char x_char;
-};
-
 
 extern struct variable *variables;
 extern bool cp_echo;