Specify aarch64 for older autotools

kokoro/release/ruby/macos/ruby/ruby_build_environment.sh

@@ -61,7 +61,7 @@ ruby --version | grep 'ruby 2.7.0'
 for v in 3.0.0 2.7.0 ; do
   ccache -c
   rake -f "$CROSS_RUBY" cross-ruby VERSION="$v" HOST=x86_64-darwin MAKE="$MAKE"
-  rake -f "$CROSS_RUBY" cross-ruby VERSION="$v" HOST=arm64-darwin MAKE="$MAKE"
+  rake -f "$CROSS_RUBY" cross-ruby VERSION="$v" HOST=aarch64-darwin MAKE="$MAKE"
 done
 set +x
 rvm use 2.5.0
@@ -70,7 +70,7 @@ ruby --version | grep 'ruby 2.5.0'
 for v in 2.6.0 2.5.1 2.4.0 2.3.0; do
   ccache -c
   rake -f "$CROSS_RUBY" cross-ruby VERSION="$v" HOST=x86_64-darwin MAKE="$MAKE"
-  rake -f "$CROSS_RUBY" cross-ruby VERSION="$v" HOST=arm64-darwin MAKE="$MAKE"
+  rake -f "$CROSS_RUBY" cross-ruby VERSION="$v" HOST=aarch64-darwin MAKE="$MAKE"
 done
 set +x
 rvm use 2.7.0