8305895: Implement JEP 450: Compact Object Headers (Experimental)
Co-authored-by: Sandhya Viswanathan <sviswanathan@openjdk.org>
Co-authored-by: Martin Doerr <mdoerr@openjdk.org>
Co-authored-by: Hamlin Li <mli@openjdk.org>
Co-authored-by: Thomas Stuefe <stuefe@openjdk.org>
Co-authored-by: Amit Kumar <amitkumar@openjdk.org>
Co-authored-by: Stefan Karlsson <stefank@openjdk.org>
Co-authored-by: Coleen Phillimore <coleenp@openjdk.org>
Co-authored-by: Axel Boldt-Christmas <aboldtch@openjdk.org>
Reviewed-by: coleenp, stefank, stuefe, phh, ihse, lmesnik, tschatzl, matsaave, rcastanedalo, vpaprotski, yzheng, egahlin
