message: Update doc/build-windows.md
  Added information how to resolve mingw compilation problem
diff: @@ -18,10 +18,26 @@ installing the toolchain will be different.
  Make sure you install the build requirements mentioned in
  [build-unix.md](/doc/build-unix.md).
  +
  Then, install the toolchains and curl:
  sudo apt-get install g++-mingw-w64-i686 mingw-w64-i686-dev g++-mingw-w64-x86-64 mingw-w64-x86-64-dev curl
  +
  +Before starting to compile you need to update mingw alternatives
  +
  + sudo update-alternatives --all
  +
  + There are 3 choices for the alternative x86_64-w64-mingw32-gcc (providing /usr/bin/x86_64-w64-mingw32-gcc) - we need to select - **1** and press enter
  +
  + Selection Path Priority Status
  + ------------------------------------------------------------
  + 0 /usr/bin/x86_64-w64-mingw32-gcc-win32 60 auto mode
  + * 1 /usr/bin/x86_64-w64-mingw32-gcc-posix 30 manual mode
  + 2 /usr/bin/x86_64-w64-mingw32-gcc-win32 60 manual mode
  +
  +Need to resolve **all mingw alternatives** in such a way.
  +
  To build executables for Windows 32-bit:
  cd depends
  