Add GlobalLock to benchmark
Add the SprayList implementation

Taken from https://github.com/jkopinsky/SprayList, commit hash
3a62fb78d475272362de3697908cc0d43b7ef745.
Include utils.h in spraylist/skiplist.h

The ALIGNED macro is defined in utils.h.
Alter SprayList val_t to uint32_t
Integrate the SprayList