Remove code for dynamically loading a trace library

No code exists within the project for building such a trace library.

This also fixes building on OS X with -Wno-deprecated-declarations
removed, since this code contained calls to deprecated functions
within #ifdef MACOS, which now are enabled when building on OS X.
Merge pull request #204 from mstorsjo/remove-dynamic-load-trace

Remove code for dynamically loading a trace library