missing optional dependecy

Please add arm-none-eabi-newlib as an optional dependency. This package is required for rpi firmware compilation.

Additional info:

• package version(s): klipper-0.12.0-2

Steps to reproduce:

1. configure klipper to build firmware for rpi RP2040

   # cd /opt/klipper
   # make menuconfig

   Select "Raspberry Pi RP2040 controller.

2. Build the firmware with make. Build fails:

     Creating symbolic link out/board
     Building out/autoconf.h
     Compiling out/src/sched.o
   src/sched.c:7:10: fatal error: setjmp.h: No such file or directory
       7 | #include <setjmp.h> // setjmp
         |          ^~~~~~~~~~
   compilation terminated.
   make: *** [Makefile:64: out/src/sched.o] Error 1

With arm-none-eabi-newlib installed the build succeeds.