a libprofcollectd wrapper in Rust

* Rewrite profcollectd frontends in Rust.
* Keep libprofcollect.hpp as a C++ header file;
  use bindgen to generate Rust FFI declarations.
* Use rust module libprofcollect as a safe wrapper to
  the extern "C" FFI functions.

Bug: 163175424
Test: run profcollectd and profcollectctl
Change-Id: Iea92dfc87621a50e47e904b7e992643fc1dc8d7a
9 files changed