macos: Fix CMAKE_OSX_ARCHITECTURES when not set

When CMAKE_OSX_ARCHITECTURES isn't set we end up with
"Packaging as: mariadb-10.4.33-osx10.19-x86_64" on arm64 builders.

Instead of implying 64bit is x86, use CMAKE_SYSTEM_PROCESSOR to form
the filename.

cmake/package_name.cmake

@@ -99,11 +99,7 @@ IF(NOT VERSION)
           SET(DEFAULT_MACHINE "${CMAKE_OSX_ARCHITECTURES}")
         ENDIF()
       ELSE()
-        IF(64BIT)
-          SET(DEFAULT_MACHINE "x86_64")
-        ELSE()
-          SET(DEFAULT_MACHINE "i386")
-        ENDIF()
+        SET(DEFAULT_MACHINE ${CMAKE_SYSTEM_PROCESSOR})
       ENDIF()
 
       IF(DEFAULT_MACHINE MATCHES "i386")