core: always initialize ExecParamters.bus_endpoint_fd to -1

Otherwise it might be passed in as 0, which is a valid fd, but usually
does not refer to a real endpoint.

src/core/mount.c

@@ -694,6 +694,7 @@ static int mount_spawn(Mount *m, ExecCommand *c, pid_t *_pid) {
                 .apply_permissions = true,
                 .apply_chroot      = true,
                 .apply_tty_stdin   = true,
+                .bus_endpoint_fd   = -1,
         };
 
         assert(m);

src/core/service.c

@@ -1054,10 +1054,10 @@ static int service_spawn(
                 **argv = NULL, **final_env = NULL, **our_env = NULL;
         const char *path;
         ExecParameters exec_params = {
-                .apply_permissions = apply_permissions,
-                .apply_chroot      = apply_chroot,
-                .apply_tty_stdin   = apply_tty_stdin,
-                .bus_endpoint_fd   = -1,
+                .apply_permissions   = apply_permissions,
+                .apply_chroot        = apply_chroot,
+                .apply_tty_stdin     = apply_tty_stdin,
+                .bus_endpoint_fd     = -1,
                 .selinux_context_net = s->socket_fd_selinux_context_net
         };
 

src/core/socket.c

@@ -1398,6 +1398,7 @@ static int socket_spawn(Socket *s, ExecCommand *c, pid_t *_pid) {
                 .apply_permissions = true,
                 .apply_chroot      = true,
                 .apply_tty_stdin   = true,
+                .bus_endpoint_fd   = -1,
         };
 
         assert(s);

src/core/swap.c

@@ -607,6 +607,7 @@ static int swap_spawn(Swap *s, ExecCommand *c, pid_t *_pid) {
                 .apply_permissions = true,
                 .apply_chroot      = true,
                 .apply_tty_stdin   = true,
+                .bus_endpoint_fd   = -1,
         };
 
         assert(s);