[Makefile] Upgrade hpp-core and hpp-plot.
[Makefile] Upgrade hpp-core and hpp-plot.

  use version 4.9.1.

jmirabel/hpp-doc,florent-lamiraux/hpp-doc,humanoid-path-planner/hpp-doc,humanoid-path-planner/hpp-doc,jmirabel/hpp-doc,florent-lamiraux/hpp-doc