add missing strerror text for key management

src/errno/__strerror.h

@@ -102,3 +102,7 @@ E(EDQUOT,       "Quota exceeded")
 E(ENOMEDIUM,    "No medium found")
 E(EMEDIUMTYPE,  "Wrong medium type")
 E(EMULTIHOP,    "Multihop attempted")
+E(ENOKEY,       "Required key not available")
+E(EKEYEXPIRED,  "Key has expired")
+E(EKEYREVOKED,  "Key has been revoked")
+E(EKEYREJECTED, "Key was rejected by service")