server: Avoid a mach port leak on Apple Silicon.

Check for Rosetta before extracting the port right, since we won't need
it in that case anyway.

server/mach.c

@@ -273,14 +273,6 @@ void set_thread_context( struct thread *thread, const context_t *context, unsign
     /* all other regs are handled on the client side */
     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 
-    if (thread->unix_pid == -1 || !process_port ||
-        mach_port_extract_right( process_port, thread->unix_tid,
-                                 MACH_MSG_TYPE_COPY_SEND, &port, &type ))
-    {
-        set_error( STATUS_ACCESS_DENIED );
-        return;
-    }
-
     if (is_rosetta())
     {
         /* Setting debug registers of a translated process is not supported cross-process
@@ -290,6 +282,14 @@ void set_thread_context( struct thread *thread, const context_t *context, unsign
         return;
     }
 
+    if (thread->unix_pid == -1 || !process_port ||
+        mach_port_extract_right( process_port, thread->unix_tid,
+                                 MACH_MSG_TYPE_COPY_SEND, &port, &type ))
+    {
+        set_error( STATUS_ACCESS_DENIED );
+        return;
+    }
+
     /* get the debug state to determine which flavor to use */
     ret = thread_get_state(port, x86_DEBUG_STATE, (thread_state_t)&state, &count);
     if (ret)