Every main()/exit() should return/use one of EXIT_ codes instead of magic numbers

src/bitcoind.cpp

@@ -126,7 +126,7 @@ bool AppInit(int argc, char* argv[])
         if (fCommandLine)
         {
             fprintf(stderr, "Error: There is no RPC client functionality in bitcoind anymore. Use the bitcoin-cli utility instead.\n");
-            exit(1);
+            exit(EXIT_FAILURE);
         }
         if (GetBoolArg("-daemon", false))
         {
@@ -177,5 +177,5 @@ int main(int argc, char* argv[])
     // Connect bitcoind signal handlers
     noui_connect();
 
-    return (AppInit(argc, argv) ? 0 : 1);
+    return (AppInit(argc, argv) ? EXIT_SUCCESS : EXIT_FAILURE);
 }