Installation instructions:

https://avrdudes.github.io/avr-libc/avr-libc-user-manual/install_tools.html

0. Always use AVR-LibC with the Binutils and GCC versions for which is
   has been configured and built.

   The recommended way to configure the tools is outside of the source
   directory and in a new, empty folder.  This means you have to specify
   the path to the configure script; indicated by ... below.

1. Build and install the current version of binutils for the AVR target.
   Releases older than 2.26 are not supported.

   $ .../configure --target=avr --disable-werror [more options]

   See https://sourceware.org/binutils/

2. Build and install the desired version of GCC for the AVR target.
   Releases older than GCC 4.8 are not supported.

   $ .../configure --target=avr --enable-languages=c,c++ [more options]

   Note that configuring GCC anywhere in the source tree is not supported,
   and that GCC needs some prerequisite host libraries like GMP, MPFR, etc.
   See https://gcc.gnu.org/install/

3. Now you can build and install AVR-LibC:
   Make sure that the avr-gcc compiler and AVR Binutils are in the PATH.
   Then run

   $ .../configure --build=`.../config.guess` --host=avr [more options]

   Then (as root, or user with write permissions to the installation directory)

   $ make
   $ make install

   Note that GNU make is required, so if GNU make is installed under a
   different name on your system (e.g. gmake), change that appropriately above.

By default, everything is installed under /usr/local.
You can change that if you configure with --prefix=/location or install with

$ make install prefix=/location

Run

$ ./configure --help

to see more configure options.  If you obtained AVR-LibC sources directly
from GIT, you will need to run

$ ./bootstrap

at toplevel AVR-LibC sources before configuring.  Use recent versions of
autoconf and automake.  Running bootstrap requires Python 2.6 or newer.
