Open62541 win32: Add python to dev environment

The autodetection of cmake used a different python for x86 builds of
msvc. Those did not have six installed. Instead, use one python for all
build variants to stay consistent.

Change-Id: Id1ad2bc320e47a68358364ff94d78993ba0b0848
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

coin/provisioning/common/windows/open62541.ps1

@@ -86,6 +86,7 @@ function PushDevEnvironment
     $adaptedPath = $env:PATH
     $jomLocation = [Environment]::GetEnvironmentVariable("CI_JOM_PATH", "Machine")
     $adaptedPath = $adaptedPath + ";" + $jomLocation
+    $adaptedPath = $adaptedPath + ";" + "C:\Python27"
     $adaptedPath = $adaptedPath + ";" + "C:\CMake\bin"
     [Environment]::SetEnvironmentVariable("PATH", $adaptedPath, "Process")
 }