RFR: 8291237: Encapsulate nmethod Deoptimization logic [v2]

[Axel Boldt-Christmas]

> The proposal is to encapsulate the nmethod mark for deoptimization logic in one place and only allow access to the `mark_for_deoptimization` from a closure object:
> ```C++
> class DeoptimizationMarkerClosure : StackObj {
> public:
>   virtual void marker_do(Deoptimization::MarkFn mark_fn) = 0;
> };
> 
> This closure takes a `MarkFn` which it uses to mark which nmethods should be deoptimized. This marking can only be done through the `MarkFn` and a `MarkFn` can only be created in the following code which runs the closure. 
> ```C++
> {
>   NoSafepointVerifier nsv;
>   assert_locked_or_safepoint(Compile_lock);
>   marker_closure.marker_do(MarkFn());
>   anything_deoptimized = deoptimize_all_marked();
> }
> if (anything_deoptimized) {
>   run_deoptimize_closure();
> }
> 
> This ensures that this logic is encapsulated and the `NoSafepointVerifier` and `assert_locked_or_safepoint(Compile_lock)` makes `deoptimize_all_marked` not having to scan the whole code cache sound.
> 
> The exception to this pattern, from `InstanceKlass::unload_class`, is discussed in the JBS issue, and gives reasons why not marking for deoptimization there is ok.
> 
> An effect of this encapsulation is that the deoptimization logic was moved from the `CodeCache` class to the `Deoptimization` class and the class redefinition logic was moved from the `CodeCache` class to the `VM_RedefineClasses` class/operation. 
> 
> Testing: Tier 1-5

Axel Boldt-Christmas has updated the pull request incrementally with three additional commits since the last revision:

 - Add assertions
 - Fix marked logic
 - Erik refactorings

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/9655/files
  - new: https://git.openjdk.org/jdk/pull/9655/files/f77f44eb..5d26ab8d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9655&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9655&range=00-01

  Stats: 339 lines in 14 files changed: 85 ins; 144 del; 110 mod
  Patch: https://git.openjdk.org/jdk/pull/9655.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9655/head:pull/9655

PR: https://git.openjdk.org/jdk/pull/9655