lnrpc+rpcserver: expose git commit hash in getinfo

lnrpc/rpc.proto

@@ -1660,6 +1660,9 @@ message GetInfoResponse {
     /// The version of the LND software that the node is running.
     string version = 14;
 
+    /// The SHA1 commit hash that the daemon is compiled with.
+    string commit_hash = 20;
+
     /// The identity pubkey of the current node.
     string identity_pubkey = 1;
 

lnrpc/rpc.swagger.json

@@ -2923,6 +2923,10 @@
           "type": "string",
           "description": "/ The version of the LND software that the node is running."
         },
+        "commit_hash": {
+          "type": "string",
+          "description": "/ The SHA1 commit hash that the daemon is compiled with."
+        },
         "identity_pubkey": {
           "type": "string",
           "description": "/ The identity pubkey of the current node."