rgmanager: randomize ASEHAagent temp files even more
rgmanager: randomize ASEHAagent temp files even more

f8943d17d4c108d44af7a42ad0fd646d4e75990e didn't didn't introduce enough
security.

Switch to mktemp(1).

Signed-off-by: Fabio M. Di Nitto <510df3d038b805d3c95a0d349043a42f16d04605@redhat.com>

asp24/resource-agents,stevenraspudic/resource-agents,stevenraspudic/resource-agents,asp24/resource-agents,asp24/resource-agents,stevenraspudic/resource-agents