Support special directory that can always skip trash

[SandyXSD]

What would you like to be added:
Configure a directory (must be empty?) so that all files created under it will be deleted directly, ignoring the trash.

Why is this needed:
Some application may create a lot of temporary files that should be purged completely no matter the trash is enabled or not.

[SandyXSD]

We may use the special attribute bit that can be set by chattr:

s      When a file with the 's' attribute set is deleted, its blocks are zeroed and written back to the disk.