Fix two problems with synchronizer.hpp:

- It's unnecessarily included in two popular headers monitorChunk.hpp and frame_<cpu>.hpp. The latter is most problematic because it's included in the middle of a class declaration!
- synchronizer.hpp includes linkedlist.hpp. This can be avoid by moving the definition of Synchronizer::PtrList into synchronizer.cpp.

These headers are included much less after this change (out of ~1000 hotspot .o files)

linkedlist.hpp 857 -> 101
synchronizer.hpp 848 -> 122
resourceHash.hpp 850 -> 270