testcrypt: fix a technically illegal forward-typedef.

Every compiler that's so far seen testcrypt.c has tolerated me writing
'typedef enum ValueType ValueType' before actually saying what 'enum
ValueType' is, but one just pointed out that it's not actually legal
standard C to do that. Moved the typedef to after the enum.

testcrypt.c

@@ -81,7 +81,6 @@ int random_byte(void)
     /* end of list */
 
 typedef struct Value Value;
-typedef enum ValueType ValueType;
 
 enum ValueType {
 #define VALTYPE_ENUM(n,t,f) VT_##n,
@@ -89,6 +88,8 @@ enum ValueType {
 #undef VALTYPE_ENUM
 }; 
 
+typedef enum ValueType ValueType;
+
 const char *const type_names[] = {
 #define VALTYPE_NAME(n,t,f) #n,
     VALUE_TYPES(VALTYPE_NAME)