Add a script to build picolibc by using make picolibc. The script works with riscv32 and riscv64 compilers.
It is installed locally to the repository with a specs-specs file containing all necessary options for correct linking.
Also a dummyfile is included for printf support which needs to be adjusted in future commits.

Include the build of our __iob implementation for printf support in the meson build of picolibc
Adjust clean target of Makefile

Move sections containing function pointers (and not code as I initially thought) to the data memory as well. Otherwise the start up code cannot load these pointers from memory.

RVController contains now all required registers for the picolibc support and interrupt is set after grace period.

Add implementation of putc and getc operations on stdin/stdout. In initialization phase base addresses of the RAM buffers are fetched. One buffer is used to write stdout output and one for "reading" from stdin.

The Controller resets the RISC-V core now with every write of '1' to the start register at 0x0, no matter in which state it is currently. This is required for proper support of the cores' debug modules.

Add an example using the picolibc with software and makefiles for both host and PE.

Delay core reset after interrupt by four cycles to avoid reset directly with new write request of Pico since this will cause that the Pico cannot be resetted properly and will hang-up in a second execution.

…by using PICOLIBC_OPTS variable