8161258: Simplify including platform files.
Summary: Include patform files with macros cpu_header() etc. Do various cleanups of macro usages. Remove _64/_32 from adlc generated files and platform .hpp files. Merge stubRoutines_x86*.hpp. Remove empty mutex_<os>* files.
Reviewed-by: dholmes, coleenp, kbarrett

8087322: Implement a Semaphore utility class
Reviewed-by: kbarrett, dholmes