fix platform detection logic on MacOS

This was tested on an M1 MacBook; it reports the machine type as
``arm64``, not ``aarch64``. The full ``uname -a`` output is:

    Darwin <NAME-REDACTED>-MBP14.local 22.2.0 Darwin Kernel Version 22.2.0: Fri Nov 11 02:03:51 PST 2022; root:xnu-8792.61.2~4/RELEASE_ARM64_T6000 arm64

This diverges from what ``System.getProperty("os.arch")`` reports
as the architecture.

Signed-off-by: Philipp Gesang <philipp.gesang@vernaio.com>

Author: phi-gamma

BuildNative

@@ -8,6 +8,11 @@ export DYNCALL_HOME=$BASE_DIR/dyncall
 
 DYNCALL_DIFF=$BASE_DIR/src/main/cpp/bridj/dyncall.diff
 
+function failed() {
+    echo "$@"
+    exit 1
+}
+
 if [[ ! -d "$DYNCALL_HOME" ]]
 then
 	$BASE_DIR/admin/checkout_and_patch_dyncall.sh $DYNCALL_DIFF || failed "Failed to checkout and patch dyncall"
@@ -40,7 +45,7 @@ function get_arch() {
         x86_64|amd64)
 	        echo x64
 	        ;;
-				aarch64)
+				aarch64|arm64)
 					echo arm64
 					;;
         arm*)

src/main/java/org/bridj/Platform.java

@@ -525,6 +525,9 @@ public static String getMachine() {
                 return "i386"; // we are running a 32 bits JVM on a 64 bits platform
             }
         }
+        if (isMacOSX() && arch.equals("aarch64")) {
+            return "arm64";
+        }
         return arch;
     }