Fix configuration on Windows
Fix configuration on Windows

value of QI_VIRTUALENV_PATH used to contain \, which cmake
does not like

Change-Id: I2f2c740635a0be341bb0f83858404001b57210bc
Reviewed-on: http://gerrit.aldebaran.lan/67115
Tested-by: gerrit
Reviewed-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>

aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild