erofs-utils: update .gitignore

Add more extensions to .gitignore.

Link: https://lore.kernel.org/r/20201202095345.10485-1-hsiangkao@aol.com
Reviewed-by: Li Guifu <bluce.lee@aliyun.com>
Signed-off-by: Gao Xiang <hsiangkao@aol.com>
1 file changed