8075210: Refactor strong root processing in order to allow G1 to evolve separately from GenCollectedHeap
Summary: Create a G1RootProcessor and move SharedHeap root processing to GenCollectedHeap
Reviewed-by: brutisso, tschatzl, ehelin

Reviewed-by: tschatzl, mgerdin, ecaspole

Reviewed-by: mgerdin, brutisso

Reviewed-by: stefank, tschatzl
Contributed-by: marcus.larsson@oracle.com

Summary: Pass on the static type G1ParPushHeapRSClosure to allow oop_iterate devirtualization
Reviewed-by: jmasa, kbarrett

Reviewed-by: asaha

Reviewed-by: jeff

Reviewed-by: mchung, dfuchs, ahgross, brutisso

Summary: Update MacroAssembler::ldf to select addressing mode depending on Address parameter.
Reviewed-by: kvn, dlong