Move type operations to another structure

Every type has free, print, check_constraints, ber_decoder, der_encoder,
xer_decoder, xer_encoder, uper_decoder, uper_encoder and outmost_tag
operations. We move them out to a separate structure asn_TYPE_operation_t.

Combined with previous logic simplification, these operations are based
on ASN.1 basic types, constructed types and string types. So we can
reduce the space occupied by asn_TYPE_descriptor_t variables.
diff --git a/skeletons/UTCTime.c b/skeletons/UTCTime.c
index 04776d7..61caf2e 100644
--- a/skeletons/UTCTime.c
+++ b/skeletons/UTCTime.c
@@ -28,9 +28,7 @@
         { APC_SEMI_CONSTRAINED, -1, -1, 0, 0 }, /* Size */
         0, 0
 };
-asn_TYPE_descriptor_t asn_DEF_UTCTime = {
-	"UTCTime",
-	"UTCTime",
+asn_TYPE_operation_t asn_OP_UTCTime = {
 	OCTET_STRING_free,
 	UTCTime_print,
 	OCTET_STRING_compare,   /* Does not deal with time zones. */
@@ -53,7 +51,13 @@
 	OCTET_STRING_decode_uper,
 	OCTET_STRING_encode_uper,
 #endif	/* ASN_DISABLE_PER_SUPPORT */
-	0, /* Use generic outmost tag fetcher */
+	0	/* Use generic outmost tag fetcher */
+};
+asn_TYPE_descriptor_t asn_DEF_UTCTime = {
+	"UTCTime",
+	"UTCTime",
+	&asn_OP_UTCTime,
+	UTCTime_constraint,
 	asn_DEF_UTCTime_tags,
 	sizeof(asn_DEF_UTCTime_tags)
 	  / sizeof(asn_DEF_UTCTime_tags[0]) - 2,