rtla: Add .gitignore file

Add .gitignore file to ignore the rtla binary.

Link: https://lore.kernel.org/linux-trace-devel/tencent_3C22A3418CD06196C2E5A84AE3EBC2281206@qq.com



Signed-off-by: Rong Tao <rongtao@cestc.cn>
Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>