cross.fish: Add classic macOS

fish/functions/cross.fish

@@ -84,6 +84,25 @@ function cross --description 'Set up cross-compilation environment'
             set -gx OBJCPPXX $CXXPP
             set -gx IPHONEOS_DEPLOYMENT_TARGET 10.0
             set -g cross_host $archs[1]-apple-darwin
+        case macos
+            if test -z "$retro68_path"
+                echo 'Please set retro68_path!'
+                return 1
+            end
+
+            set PATH $retro68_path/bin $PATH
+
+            switch $argv[2]
+                case m68k
+                    set -g cross_host m68k-apple-macos
+                case ppc
+                    set -g cross_host powerpc-apple-macos
+            end
+
+            if test (count $argv) != 2 -o -z "$cross_host"
+                echo 'Usage: cross macos m68k|ppc'
+                return 1
+            end
         case mingw
             set -l pkg
             switch $argv[2]