Fix misuse of cman FD in fenced
 

This patch fixes a caching of the cman file descriptor in fenced, which
the header file explicitly says you should not do.


I have seen symptoms that are consistent with this going wrong and while
I can't prove that this is the cause it looks highly likely.


The patch is against the RHEL5 branch, but the bug also exists in RHEL6
and upstream versions


There also is a chance that this mistake exists in other cluster
daemons, I haven't checked as yet.