vendor/libhyperkit: update github.com/zchee/libhyperkit to latest

- kexec.c commit message
  - Use the initrd_addr_max value from the kernel header if the
    kernel version is 2.03 or newer. Use hardcoded(0x37ffffff) value
    if older.
  - Compare the initrd_max and memory.size, and re-assign if
    initrd_max is larger.
  - Add ALIGNDOWN for ramdisk_start, uses prevent to go past the
    address limit.
  - Based on qemu/hw/i386/pc.c

Signed-off-by: Koichi Shiraishi <zchee.io@gmail.com>

Author: zchee