Bump max symbol length to 64.

And move the constant to conf.h header.

Thanks to Alexander Chernikov for the patch.

conf/cf-lex.l

@@ -61,7 +61,6 @@ static struct keyword *kw_hash[KW_HASH_SIZE];
 static int kw_hash_inited;
 
 #define SYM_HASH_SIZE 128
-#define SYM_MAX_LEN 32
 
 struct sym_scope {
   struct sym_scope *next;		/* Next on scope stack */

conf/conf.h

@@ -108,6 +108,8 @@ struct symbol {
   char name[1];
 };
 
+#define SYM_MAX_LEN 64
+
 /* Remember to update cf_symbol_class_name() */
 #define SYM_VOID 0
 #define SYM_PROTO 1