write_elf32_notes/wirte_elf64_notes use fd_write_vmcore to write elf notes to
vmcore. Adding parameter "WriteCoreDumpFunction f" makes it available to choose
the method of writing elf notes

Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>