debian/control: add loong64 support

Dear Maintainers,

I have added support for the "loong64" architecture in the debian/control file of the naev software package. The updated Architecture field now includes "loong64" along with other architectures:

Architecture: alpha amd64 arm64 armel armhf hppa i386 ia64 loong64 m68k mips mips64el mipsel powerpc powerpcspe ppc64 ppc64el riscv64 s390x sh4 sparc64 x32

Thank you for your attention to this update.