[Picolibc] Integrating Picolibc into a GCC toolchain

[R. Diez]

>> https://github.com/rdiez/JtagDue/blob/master/Toolchain/Tools/GeneratePicolibcCrossFile.sh

> I'll try to implement that in the next days without using the external tool 'expr'.

I have done that too.

Let me know if you need anything else.

Regards,
   rdiez