Add aarch64-multiplatform-musl to ci

ci.nix

@@ -1,6 +1,6 @@
 # 'supportedSystems' restricts the set of systems that we will evaluate for. Useful when you're evaluating
 # on a machine with e.g. no way to build the Darwin IFDs you need!
-{ ifdLevel ? 3
+{ ifdLevel ? 2
 # Whether or not we are evaluating in restricted mode. This is true in Hydra, but not in Hercules.
 , restrictEval ? false
 , checkMaterialization ? false
@@ -78,7 +78,9 @@
   } // lib.optionalAttrs (system == "x86_64-linux" && nixpkgsName == "unstable" && __elem compiler-nix-name ["ghc8107" "ghc902" "ghc922" "ghc923" "ghc924" "ghc926" "ghc927" "ghc928" "ghc945" "ghc962"]) {
     # Musl cross only works on linux
     # aarch64 cross only works on linux
-    inherit (lib.systems.examples) musl64 aarch64-multiplatform;
+    inherit (lib.systems.examples) musl64 aarch64-multiplatform aarch64-multiplatform-musl;
+  } // lib.optionalAttrs (system == "aarch64-linux" && nixpkgsName == "unstable" && __elem compiler-nix-name ["ghc8107" "ghc902" "ghc922" "ghc923" "ghc924" "ghc926" "ghc927" "ghc928" "ghc945" "ghc961"]) {
+    inherit (lib.systems.examples) aarch64-multiplatform-musl;
   } // lib.optionalAttrs (system == "x86_64-linux" && nixpkgsName == "unstable" && __elem compiler-nix-name ["ghc927" "ghc928"]) {
     # TODO fix this for the compilers we build with hadrian (ghc >=9.4)
     inherit (lib.systems.examples) aarch64-multiplatform-musl;