MFC r267897: MFV r267843:

Update file/libmagic to 5.19.
MFC r267887:

Correct buffer size.

Submitted by:	Sascha Wildner <swildner dragonflybsd org>
MFC r267886:

Use correct length for buffer.

Submitted by:	Sascha Wildner <swildner dragonflybsd org>
Correct memset size.

Submitted by:	Sascha Wildner (swildner at dragonflybsd dot org)
Reviewed by:	Kashyap Desai <kashyap.desai avagotech.com>