Re-order MAC and DAC checks in shmget() in order to give precedence to the MAC result, as well as avoid losing the DAC check result when MAC is enabled.
Re-order MAC and DAC checks in shmget() in order to give precedence to
the MAC result, as well as avoid losing the DAC check result when MAC
is enabled.

MFC after:	3 days
Reported by:	Patrick LeBlanc <Patrick dot LeBlanc at sparta dot com>

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