Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
to this commit, "env BLOCKSIZE=4X df" prints not only "4X: unknown
blocksize" as expected, but sometimes also "maximum blocksize is 1G"
and "minimum blocksize is 512" depending on what happened to be on
the stack.
Found by: LLVM/Clang Static Checker