cmd: Do not use comparison to NULL

checkpatch emits two warnings of type:

    CHECK: Comparison to NULL could be written "!foo"

Prefer `(!foo)` instead of `(foo == NULL)`.

Do not use comparison to NULL, use !foo

Signed-off-by: Tobin C. Harding <me@tobin.cc>

src/lxc/cmd/lxc_monitord.c

@@ -208,7 +208,7 @@ static int lxc_monitord_sock_accept(int fd, uint32_t events, void *data,
 
 		clientfds = realloc(mon->clientfds,
 				    (mon->clientfds_size + CLIENTFDS_CHUNK) * sizeof(mon->clientfds[0]));
-		if (clientfds == NULL) {
+		if (!clientfds) {
 			ERROR("Failed to realloc memory for %d client file descriptors",
 			      mon->clientfds_size + CLIENTFDS_CHUNK);
 			goto err1;

src/lxc/cmd/lxc_user_nic.c

@@ -752,7 +752,7 @@ static char *get_nic_if_avail(int fd, struct alloted_s *names, int pid,
 		lxc_strmunmap(buf, sb.st_size);
 	}
 
-	if (owner == NULL)
+	if (!owner)
 		return NULL;
 
 	ret = snprintf(nicname, sizeof(nicname), "vethXXXXXX");