cmake: jsoncpp: fix include directory
cmake: jsoncpp: fix include directory

Avoid file collision with the package json-c.

Change-Id: I919244d825c6993e5cf9f3176cac8a63bf25b6c5
Reviewed-on: http://gerrit.aldebaran.lan:8080/7523
Reviewed-by: smartin <edaf33f3e53483e687d304aa81a03bb5a17b9ddf@aldebaran-robotics.com>
Tested-by: smartin <edaf33f3e53483e687d304aa81a03bb5a17b9ddf@aldebaran-robotics.com>

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