Merge pull request #72727 from oxalica/mips-parse

lib.systems: handle mips family properly

lib/systems/default.nix

···
         else if final.isAarch64 then "arm64"
         else if final.isx86_32 then "x86"
         else if final.isx86_64 then "ia64"
+        else if final.isMips then "mips"
         else final.parsed.cpu.name;
 
       qemuArch =

lib/systems/parse.nix

···
         }
       ];
     };
+    gnuabi64     = { abi = "64"; };
 
     musleabi     = { float = "soft"; };
     musleabihf   = { float = "hard"; };