K 10
svn:author
V 4
bapt
K 8
svn:date
V 27
2016-05-27T11:46:54.229303Z
K 7
svn:log
V 433
Improve error message when failing to open a backing file

When bhyve cannot open a backing file, it now says explicitly which file
could not be opened

Note that the change has only be maed in block_if.c and not in
pci_virtio_block.c as the error will always be catched by the first

PR:		202321 (different patch)
Reviewed by:	grehan
MFC after:	3 day
Sponsored by:	Gandi.net
Differential Revision:	https://reviews.freebsd.org/D6576

END