swig/python.cmake: keep number of include dirs reasonable
swig/python.cmake: keep number of include dirs reasonable

If you had lots of dependencies, you would end up
adding lots and lots of include dirs, causing 'command line too long'
errors

Change-Id: Id3528488e564de88687b962b6c12352da990c54d
Reviewed-on: http://gerrit.aldebaran.lan:8080/894
Reviewed-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>
Tested-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>

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