Correctly validate inputs to the i386_get_ldt syscall.
Correctly validate inputs to the i386_get_ldt syscall.

Security: FreeBSD-SA-05:07.ldt

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase