message: Update doc/build-windows.md
  Updated way to resolve alternatives
diff: @@ -23,22 +23,17 @@ 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
  +sudo update-alternatives --set x86_64-w64-mingw32-gcc /usr/bin/x86_64-w64-mingw32-gcc-posix
  -Need to resolve **all mingw alternatives** in such a way.
  +sudo update-alternatives --set x86_64-w64-mingw32-g++ /usr/bin/x86_64-w64-mingw32-g++-posix
  +********************
  To build executables for Windows 32-bit:
  +------------------
  cd depends
  make HOST=i686-w64-mingw32 -j4
  