command: Fix handling of buffer passing in args[] on 64bit mcu

If the buffer pointer can't fit in a uint32_t then pass a relative
buffer offset instead.  This fixes buffer handling on 64bit linux
mcus.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/command.c

@@ -18,12 +18,16 @@ static uint8_t next_sequence = MESSAGE_DEST;
 static uint32_t
 command_encode_ptr(void *p)
 {
+    if (sizeof(size_t) > sizeof(uint32_t))
+        return p - console_receive_buffer();
     return (size_t)p;
 }
 
 void *
 command_decode_ptr(uint32_t v)
 {
+    if (sizeof(size_t) > sizeof(uint32_t))
+        return console_receive_buffer() + v;
     return (void*)(size_t)v;
 }