Add /usr/local/bin to the end of the default path

this was initially removed as it resulted in programs in /etc/profile.d searching /usr/local/bin, which if the NFS server had hung resulted in ec2-user not being able to log in
subsequently verified that it seems safe to add it to the end of the path, obviously subject to not having anything called from profile that exists in /usr/local


Former-commit-id: deccb12e