rpc: Add AddrIndex and TxIndex bools to getinfo.

These reflect if the dcrd indexes are enabled.

docs/json_rpc_api.mediawiki

@@ -1463,7 +1463,9 @@ of the best block.
 : <code>difficulty</code>: <code>(numeric)</code> the current target difficulty.
 : <code>testnet</code>: <code>(boolean)</code> whether or not server is using testnet.
 : <code>relayfee</code>: <code>(numeric)</code> the minimum relay fee for non-free transactions in DCR/KB.
-<code>{"version": n,"protocolversion": n, "blocks": n, "timeoffset": n, "connections": n, "proxy": "host:port", "difficulty": n.nn, "testnet": true or false, "relayfee": n.nn}</code>
+: <code>addrindex</code>: <code>(boolean)</code> whether or not server has address index enabled.
+: <code>txindex</code>: <code>(boolean)</code> whether or not server has transaction index enabled.
+<code>{"version": n,"protocolversion": n, "blocks": n, "timeoffset": n, "connections": n, "proxy": "host:port", "difficulty": n.nn, "testnet": true or false, "relayfee": n.nn, "addrindex": true or false, "txindex": true or false}</code>
 |-
 !Example Return
 |<code>{"version": 70000, "protocolversion": 70001, "blocks": 298963, "timeoffset": 0, "connections": 17, "proxy": "", "difficulty": 8000872135.97, "testnet": false,"relayfee": 0.00001}</code>

rpc/jsonrpc/types/chainsvrresults.go

@@ -193,6 +193,8 @@ type InfoChainResult struct {
 	TestNet         bool    `json:"testnet"`
 	RelayFee        float64 `json:"relayfee"`
 	Errors          string  `json:"errors"`
+	AddrIndex       bool    `json:"addrindex"`
+	TxIndex         bool    `json:"txindex"`
 }
 
 // GetMempoolInfoResult models the data returned from the getmempoolinfo

rpcserver.go

@@ -2345,6 +2345,8 @@ func handleGetInfo(_ context.Context, s *rpcServer, cmd interface{}) (interface{
 		Difficulty:      getDifficultyRatio(best.Bits, s.cfg.ChainParams),
 		TestNet:         cfg.TestNet,
 		RelayFee:        cfg.minRelayTxFee.ToCoin(),
+		AddrIndex:       cfg.AddrIndex,
+		TxIndex:         cfg.TxIndex,
 	}
 
 	return ret, nil

rpcserverhelp.go

@@ -503,6 +503,8 @@ var helpDescsEnUS = map[string]string{
 	"infochainresult-testnet":         "Whether or not server is using testnet",
 	"infochainresult-relayfee":        "The minimum relay fee for non-free transactions in DCR/KB",
 	"infochainresult-errors":          "Any current errors",
+	"infochainresult-addrindex":       "Whether or not server has address index enabled",
+	"infochainresult-txindex":         "Whether or not server has transaction index enabled",
 
 	// InfoWalletResult help.
 	"infowalletresult-version":         "The version of the server",