64 bit fixes

[tomwj]

No description provided.

[rgov]

You can just remove the CFLAGS= line for Darwin, there's no need to override the compiler's default behavior of selecting the native architecture.

It works OK on Apple silicon:

./pirate-loader_mac --dev=/dev/cu.usbserial-A105BMH4 --hello
+++++++++++++++++++++++++++++++++++++++++++
  Pirate-Loader for BP with Bootloader v4+  
  Loader version: 1.0.2  OS: S
+++++++++++++++++++++++++++++++++++++++++++

Opening serial device /dev/cu.usbserial-A105BMH4...OK
Configuring serial port settings...OK
Sending Hello to the Bootloader...OK

Device ID: PIC24FJ64GA002 [d4]
Bootloader version: 1,02