RFR: 8255782: Turn UseTLAB and ResizeTLAB from product_pd to product, defaulting to "true"

[Aleksey Shipilev]

When doing Zero VM performance investigations, I realized that `UseTLAB` is disabled there by default. 

That is effectively because `UseTLAB` is currently `product_pd` (defined in `gc_globals.hpp`), and it is enabled for every platform with C1 and C2 ports (in their respective `c1/c2_globals.hpp`). `compiler_globals.hpp` has a block that defines `UseTLAB` to `false` when no C1/C2/JVMCI is present.

Not only this is awkward -- GC flag is managed by Compiler globals! -- it makes Zero awkward to opt-in to `UseTLAB` in `*_zero_globals.hpp`, because `compiler_globals.hpp` already defines it. I think we can make this all better by turning TLAB flags from `product_pd` to `product`, and defaulting them to `true`. This matches what every current Server/Minimal VM config has, and would implicitly enable `UseTLAB` and `ResizeTLAB` for Zero, as well as for builds with `--with-jvm-features=-compiler1,-compiler-2,-jvmci` (in case anyone actually builds it, that is only with template interpreter).

On the downside, this shuts the door for new platform ports to disable TLAB flags by default to ease porting. But I believe the same can be achieved by turning these flags off in `arguments.cpp` under the special platform defines, while TLAB enablement work is in progress.

Additional testing:
  - [x] Linux x86_64 Zero ad-hoc runs
  - [x] Linux x86_64 `--with-jvm-features=-compiler1,-compiler-2,-jvmci,*` builds

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Commit messages:
 - Prototype

Changes: https://git.openjdk.java.net/jdk/pull/1019/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1019&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255782
  Stats: 25 lines in 12 files changed: 1 ins; 22 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1019.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1019/head:pull/1019

PR: https://git.openjdk.java.net/jdk/pull/1019