Fix a bug that allows NFS clients to issue READDIR on files.

PR:		kern/178016
Security:	CVE-2013-3266
Security:	FreeBSD-SA-13:05.nfsserver
Approved by:	so
Fix a bug that allows NFS clients to issue READDIR on files.

(files missing from previous commit)

PR:		kern/178016
Security:	CVE-2013-3266
Security:	FreeBSD-SA-13:05.nfsserver
Approved by:	so
Fix a bug that allowed a tracing process (e.g. gdb) to write
to a memory-mapped file in the traced process's address space
even if neither the traced process nor the tracing process had
write access to that file.

Security:	CVE-2013-2171
Security:	FreeBSD-SA-13:06.mmap
Approved by:	so