error: Add VIR_ERR_DEPRECATED error code

Allow a simple programatic check that a given feature is no longer
supported by introducing a separate error code for this scenario.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

include/libvirt/virterror.h

@@ -329,6 +329,7 @@ typedef enum {
     VIR_ERR_INVALID_NETWORK_PORT = 105, /* invalid network port object */
     VIR_ERR_NETWORK_PORT_EXIST = 106,   /* the network port already exist */
     VIR_ERR_NO_NETWORK_PORT = 107,      /* network port not found */
+    VIR_ERR_DEPRECATED = 108,           /* configuration or operation is no longer supported */
 
 # ifdef VIR_ENUM_SENTINELS
     VIR_ERR_NUMBER_LAST

src/util/virerror.c

@@ -1235,6 +1235,10 @@ const virErrorMsgTuple virErrorMsgStrings[VIR_ERR_NUMBER_LAST] = {
     [VIR_ERR_NO_NETWORK_PORT] = {
         N_("network port not found"),
         N_("network port not found: %s") },
+    [VIR_ERR_DEPRECATED] = {
+        N_("operation or configuration no longer supported"),
+        "%s",
+    },
 };