[host] service: introduce fatal errors for ivshmem failures

Also for failure to parse command line. For these errors, restarting
with exponential backoff will not help: no amount of restarting the
service could possibly make the ivshmem device exist or larger, so
we shouldn't try.

host/platform/Windows/src/service.c

@@ -717,6 +717,10 @@ VOID WINAPI SvcMain(DWORD dwArgc, LPTSTR *lpszArgv)
               break;
             }
 
+            case LG_HOST_EXIT_FATAL:
+              doLog("Host application failed to start with fatal error; will not restart\n");
+              goto stopped;
+
             default:
               doLog("Host application failed due to unknown error; restarting\n");
               break;