Loongson support; more support for x86 and ARM

[nihil-admirari]

Xray-core provides Loongson binaries, but install script doesn't handle this architecture. Adding the following case should be enough:

loongarch64 )
    MACHINE=loong64
    ;;

Also, according to https://stackoverflow.com/a/78630608, there are i[3456]86 versions of x86, and a plethora of armv5*–armv7*.