Squashed 'external/trappy/' changes from e5e53c4f5..cc2c57953

cc2c57953 Merge pull request #299 from douglas-raillard-arm/add_funcgraph
fdaebf7ef ftrace: Add support for funcgraph_entry and funcgraph_exit events

git-subtree-dir: external/trappy
git-subtree-split: cc2c579533ac1d09e93e497b5d1844b5575531a5