windows: Update windows prereq script & precompiled environment download

docs/get-started/windows-setup.rst

@@ -13,7 +13,7 @@ Toolchain Setup
 
 The quick setup is to download the Windows all-in-one toolchain & MSYS zip file from dl.espressif.com:
 
-https://dl.espressif.com/dl/esp32_win32_msys2_environment_and_toolchain-20170330.zip
+https://dl.espressif.com/dl/esp32_win32_msys2_environment_and_toolchain-20170918.zip
 
 Unzip the zip file to ``C:\`` (or some other location, but this guide assumes ``C:\``) and it will create an ``msys32`` directory with a pre-prepared environment.
 

tools/windows/windows_install_prerequisites.sh

@@ -44,7 +44,7 @@ python -m pip install --upgrade pip
 pip install pyserial
 
 # Automatically download precompiled toolchain, unpack at /opt/xtensa-esp32-elf/
-TOOLCHAIN_ZIP=xtensa-esp32-elf-win32-1.22.0-70-gfa0bad1-5.2.0.zip
+TOOLCHAIN_ZIP=xtensa-esp32-elf-win32-1.22.0-73-ge28a011-5.2.0.zip
 echo "Downloading precompiled toolchain ${TOOLCHAIN_ZIP}..."
 cd ~
 curl -LO --retry 10 http://dl.espressif.com/dl/${TOOLCHAIN_ZIP}