Fix memleak and silence Coverity defects
    
    Some of these are not real defects, because we are guaranteed to have valid
    context in some functions, and checks are not necessary.
    I added the checks anyway in order to silence Coverity on these issues.
    
    One meleak on error condition was fixed in
    daemons/ipa-kdb/ipa_kdb_pwdpolicy.c
    
    Silence errors in ipa-client/ipa-getkeytab.c, the code looks wrong, but it is
    actually fine as we count before hand so we never actually use the wrong value
    that is computed on the last pass when p == 0
    
    Fixes: https://fedorahosted.org/freeipa/ticket/2488