Add a sample to test C++ exceptions support (#432) (#434)

Add a sample to test C++ exceptions support

Refactor libraries with exceptions (#354)

Rework of libraries with exceptions
so one can use them with --sysroot parameter
to clang compiler.

Update CHANGELOG and picolibc version

Restore trailing whitespaces in patch

Without these the patch is detected as corrupted
and the Windows build fails.

Add libunwind license

We package libunwind so we also need to distribute its license.

Adjust revisions and patches for LLVM 15

Fix version numbers in documentation

Add Mingw-w64 licenses and version

This patch adds several license files pertinent to the runtime DLLs
that are part of the Mingw-w64 project, specifically:
* COPYING3.GCC - GPL v3 - applies to libstdc++ and libgcc
* COPYING.RUNTIME - GCC Runtime library exception - applies to
  libstdc++ and libgcc
* COPYING.MinGW-w64-runtime.txt - applies to libstdc++, libgcc and
  libwinpthread

These licenses are included in the binary distribution when the
corresponding DLLs are included in the distribution.

Also this patch adds Mingw-w64 version information to VERSION.txt
when compiling with Mingw-w64.