Free memory allocated in various functions
1. Add 'ref_cnt' field to asn1p_expr_t.
2. Initialize 'ref_cnt' field to zero when asn1p_expr_t is allocated.
3. Increase 'ref_cnt' field when asn1p_expr_t is cloned by asn1p_value_fromtype().
4. If 'ref_cnt' field of asn1p_expr_t is larger than zero, then asn1p_expr_free() only decrease its value.
5. Free memory pointed by fields of asn1p_expr_t and itself when 'ref_cnt' is zero and asn1p_expr_free() called.
6. Call asn1p_delete(asn) in main().
diff --git a/libasn1parser/asn1p_expr.h b/libasn1parser/asn1p_expr.h
index 89d939a..dfeaa25 100644
--- a/libasn1parser/asn1p_expr.h
+++ b/libasn1parser/asn1p_expr.h
@@ -216,6 +216,7 @@
asn1p_value_t *default_value; /* For EM_DEFAULT case */
} marker;
int unique; /* UNIQUE */
+ int ref_cnt; /* reference count */
/*
* Whether automatic tagging may be applied for subtypes.