Migrate profcollectd's libflags bindings from bindgen to cxx.

This should both simplify the code and fix some errors in the existing
implementation.

Bug: 182498247
Test: Build
Change-Id: I2a5bcbcac407ba0bb41d4884b99fe8a55113ae38
(cherry picked from commit c8fb4177717b50c3c5789011e4ab795771a62102)
5 files changed