add const

libasn1parser/asn1p_constr.c

@@ -142,7 +142,7 @@ asn1p_constraint_prepend(asn1p_constraint_t *before, asn1p_constraint_t *what) {
 }
 
 
-char *
+const char *
 asn1p_constraint_type2str(enum asn1p_constraint_type_e type) {
 	switch(type) {
 	case ACT_INVALID:

libasn1parser/asn1p_constr.h

@@ -69,7 +69,7 @@ typedef struct asn1p_constraint_s {
 } asn1p_constraint_t;
 
 /* Human-readable constraint type description */
-char *asn1p_constraint_type2str(enum asn1p_constraint_type_e);
+const char *asn1p_constraint_type2str(enum asn1p_constraint_type_e);
 
 /*
  * Constructors and a recursive destructor.