[build][trunk] Add triple lib to config, lib symlink workaround

[dpalermo]

- Upstream has introduced a triple lib subdir for target libraries
  (requires another search path in the cfg)
- Building with -DBUILD_SHARED_LIBS=ON causes compiler so's to appear
  as dependencies in libomptarget.so which are no longer found
- add triple lib to cfg
- symlink triple lib subdir objects back to lib to allow for libs to be found
  (workaround until -frtlib-add-rpath solution can be made)