#18 Update config.guess to add riscv64 architecture support for xine-lib

[a1ca7raz]

Hi,
I am packaging this project for Arch Linux RISC-V and I noticed that config.guess script this project use is too old to recognize riscv64 arch. This script should be updated to support riscv64 arch.
To update this script manually while packaging, I ran this command before run configure script:
autoreconf -fi && autoupdate -f
then this problem should be fixed.
Thx.