Added submodule update

.appveyor.yml

@@ -27,9 +27,12 @@ environment:
 
 
 install:
+  # Checking submodule(s) out
+  - git submodule update --init --recursive
   # Install Python (from the official .msi of http://python.org) and pip when
   # not already installed.
-  - ps: if (-not(Test-Path($env:PYTHON))) { & appveyor\install.ps1 -python -pip -stdint }
+  - ps: if (-not(Test-Path($env:PYTHON))) { & appveyor\install.ps1 -python -pip }
+  - ps: appveyor\install.ps1 -stdint
 
   # Prepend newly installed Python to the PATH of this build (this cannot be
   # done from inside the powershell script as it would require to restart