The text-based mount command displays the rather inexplicable "mount:

internal error" whenever it encounters a problem that is entirely
unexpected by its designers.

Let's beef that error message up to include instructions about reporting
the problem, and fix the error code returned by the mount option rewriting
logic so that also will no longer report "internal error".  An error in there
should generally only occur if there was an invalid mount option specified.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>