Update syslinux to version 4.04 / rev 70 via SR 1126911
    
    https://build.opensuse.org/request/show/1126911
    by user snwint + anag+factory
    - Build the system installable binaries with RPM_OPT_FLAGS, to allow
      utilization of stack-protector and FORTIFY_SOURCE. (bsc#1211640) (forwarded request 1089159 from msmeissn)