Back out previous commit. Even though statfs(2) can take a regular

file as an argument, it may still fail for the same reasons that
open(2) can.

Pointed out by:	Jilles Tjoelker
Apporived by:	bmilekic (mentor)

lib/libc/sys/statfs.2

@@ -175,6 +175,10 @@ The
 system call
 fails if one or more of the following are true:
 .Bl -tag -width Er
+.It Bq Er ENOTDIR
+A component of the path prefix of
+.Fa path
+is not a directory.
 .It Bq Er ENAMETOOLONG
 The length of a component of
 .Fa path