builder/vmware: compile host_ip on every platform

builder/vmware/host_ip.go

-// +build darwin freebsd linux netbsd openbsd
-
 package vmware
 
 // Interface to help find the host IP that is available from within

builder/vmware/host_ip_vmnetnatconf.go

@@ -57,7 +57,9 @@ func (*VMnetNatConfIPFinder) HostIP() (string, error) {
 			break
 		}
 
-		return "", err
+		if err != nil {
+			return "", err
+		}
 	}
 
 	return "", errors.New("host IP not found in NAT config")