Interface proposal : pull request 3

[yoann-heitz]

This is the third pull request for the proposal for a plugin interface for the rocprof command. In this pull request, the signatures of the flushing functions are standardized for every API/kind of event.

The signatures of all flushing function are now of this kind : void <API>_flush_cb(<API>_trace_entry_t *entry) Where <API> is the kind of event or API that is traced and <API>_trace_entry_t is a wrapping data structure containing the payloads of the traced events.

Relative to the second pull request, this one starts at commit 65161e2