Add extension free function.

(Imported from upstream's 984a30423d70126ed1df30e4b52962398cdaa9b6.)

crypto/x509v3/v3_lib.c

diff --git a/crypto/x509v3/v3_lib.c b/crypto/x509v3/v3_lib.c
index b921499..0119b45 100644
--- a/crypto/x509v3/v3_lib.c
+++ b/crypto/x509v3/v3_lib.c
@@ -120,6 +120,27 @@
 	return X509V3_EXT_get_nid(nid);
 }
 
+int X509V3_EXT_free(int nid, void *ext_data)
+{
+	    const X509V3_EXT_METHOD *ext_method = X509V3_EXT_get_nid(nid);
+	    if (ext_method == NULL)
+	    {
+		    OPENSSL_PUT_ERROR(X509V3, X509V3_EXT_free, X509V3_R_CANNOT_FIND_FREE_FUNCTION);
+		    return 0;
+	    }
+
+	    if (ext_method->it != NULL)
+		    ASN1_item_free(ext_data, ASN1_ITEM_ptr(ext_method->it));
+	    else if (ext_method->ext_free != NULL)
+		    ext_method->ext_free(ext_data);
+	    else
+	    {
+		    OPENSSL_PUT_ERROR(X509V3, X509V3_EXT_free, X509V3_R_CANNOT_FIND_FREE_FUNCTION);
+		    return 0;
+	    }
+
+	    return 1;
+}
 
 int X509V3_EXT_add_list(X509V3_EXT_METHOD *extlist)
 {

crypto/x509v3/x509v3.h

diff --git a/crypto/x509v3/x509v3.h b/crypto/x509v3/x509v3.h
index 5b98441..ecddb0f 100644
--- a/crypto/x509v3/x509v3.h
+++ b/crypto/x509v3/x509v3.h
@@ -783,6 +783,7 @@
 #define X509V3_F_X509_PURPOSE_add 153
 #define X509V3_F_SXNET_add_id_INTEGER 154
 #define X509V3_F_i2v_AUTHORITY_INFO_ACCESS 155
+#define X509V3_F_X509V3_EXT_free 156
 #define X509V3_R_INVALID_BOOLEAN_STRING 100
 #define X509V3_R_POLICY_SYNTAX_NOT_CURRENTLY_SUPPORTED 101
 #define X509V3_R_INVALID_NAME 102
@@ -851,5 +852,6 @@
 #define X509V3_R_DUPLICATE_ZONE_ID 165
 #define X509V3_R_EXTENSION_NOT_FOUND 166
 #define X509V3_R_INVALID_ASNUMBER 167
+#define X509V3_R_CANNOT_FIND_FREE_FUNCTION 168
 
 #endif

crypto/x509v3/x509v3_error.c

diff --git a/crypto/x509v3/x509v3_error.c b/crypto/x509v3/x509v3_error.c
index 6a8d582..e87ddfc 100644
--- a/crypto/x509v3/x509v3_error.c
+++ b/crypto/x509v3/x509v3_error.c
@@ -24,6 +24,7 @@
   {ERR_PACK(ERR_LIB_X509V3, X509V3_F_SXNET_get_id_ulong, 0), "SXNET_get_id_ulong"},
   {ERR_PACK(ERR_LIB_X509V3, X509V3_F_X509V3_EXT_add, 0), "X509V3_EXT_add"},
   {ERR_PACK(ERR_LIB_X509V3, X509V3_F_X509V3_EXT_add_alias, 0), "X509V3_EXT_add_alias"},
+  {ERR_PACK(ERR_LIB_X509V3, X509V3_F_X509V3_EXT_free, 0), "X509V3_EXT_free"},
   {ERR_PACK(ERR_LIB_X509V3, X509V3_F_X509V3_EXT_i2d, 0), "X509V3_EXT_i2d"},
   {ERR_PACK(ERR_LIB_X509V3, X509V3_F_X509V3_EXT_nconf, 0), "X509V3_EXT_nconf"},
   {ERR_PACK(ERR_LIB_X509V3, X509V3_F_X509V3_add1_i2d, 0), "X509V3_add1_i2d"},
@@ -77,6 +78,7 @@
   {ERR_PACK(ERR_LIB_X509V3, 0, X509V3_R_BAD_OBJECT), "BAD_OBJECT"},
   {ERR_PACK(ERR_LIB_X509V3, 0, X509V3_R_BN_DEC2BN_ERROR), "BN_DEC2BN_ERROR"},
   {ERR_PACK(ERR_LIB_X509V3, 0, X509V3_R_BN_TO_ASN1_INTEGER_ERROR), "BN_TO_ASN1_INTEGER_ERROR"},
+  {ERR_PACK(ERR_LIB_X509V3, 0, X509V3_R_CANNOT_FIND_FREE_FUNCTION), "CANNOT_FIND_FREE_FUNCTION"},
   {ERR_PACK(ERR_LIB_X509V3, 0, X509V3_R_DIRNAME_ERROR), "DIRNAME_ERROR"},
   {ERR_PACK(ERR_LIB_X509V3, 0, X509V3_R_DISTPOINT_ALREADY_SET), "DISTPOINT_ALREADY_SET"},
   {ERR_PACK(ERR_LIB_X509V3, 0, X509V3_R_DUPLICATE_ZONE_ID), "DUPLICATE_ZONE_ID"},