MFV r273688:

Update filesystems magic.  This fixes a regression introduced by
libmagic 5.19 which prevents file(1) to show more verbose information
about a MBR.

Submitted by:	madpilot
MFC after:	2 weeks


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273689 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f