totemconfig.c: don't hard-code "128"...

• exec/totemconfig.c (read_keyfile): Don't hard-code "128".

Use sizeof(...) instead.
Avoid duplicate "close(fd)" calls.

git-svn-id: http://svn.fedorahosted.org/svn/corosync/trunk@2039 fd59a12c-fef9-0310-b244-a6a79926bd2f