security: Add DAC to security_drivers

Currently, if users set 'security_driver="dac"' in qemu.conf libvirtd
fails to initialize as DAC driver is not found because it is missing
in our security drivers array.

src/security/security_driver.c

@@ -35,6 +35,7 @@
 # include "security_apparmor.h"
 #endif
 
+#include "security_dac.h"
 #include "security_nop.h"
 
 #define VIR_FROM_THIS VIR_FROM_SECURITY
@@ -46,6 +47,7 @@ static virSecurityDriverPtr security_drivers[] = {
 #ifdef WITH_SECDRIVER_APPARMOR
     &virAppArmorSecurityDriver,
 #endif
+    &virSecurityDriverDAC,
     &virSecurityDriverNop, /* Must always be last, since it will always probe */
 };