RFR: 8291752: AArch64: Remove check_emit_size parameter from trampoline_call [v2]

[Evgeny Astigeevich]

> `MacroAssembler::trampoline_call` can skip generation of a trampoline stub if C2 phase output is in the checking emitted code size mode. If it is not C2 compilation, `trampoline_call` always generates a trampoline stub. 
> 
> `gen_continuation_enter` as a part of C2 compilation needed to disable the functionality above. Now `trampoline_call` has the `check_emit_size` which allows to disable the functionality completely. Its default value is `true` which means the functionality is enabled.
> 
> There are problems:
> - C2 specific code which must be properly guarded if it is not C2 compilation. The code has the risk of undefined behaviour (UB). It is done with `is_c2_compile`. [JDK-8291654](https://bugs.openjdk.org/browse/JDK-8291654) is an example of changes caused UB.
> - The default value of `check_emit_size`. The current value `true` allows C1 to access the C2 specific code. Setting the default value to `false` will require to review and to update every existing use of `trampoline_call`. It will complicate uses of `trampoline_call`: each time a decision needs to be done - use or not use the default.
> 
> Summary of changes:
> - Have a virtual `emit_trampoline_stub` which is privately overridden in `C2_MacroAssembler`. The overridden  version does not emit a stub if C2 phase output is in the checking emitted code size mode.
> - `emit_trampoline_stub` returns `bool` instead of `address` because `address` is only used to check the success of a call.
> - `check_emit_size` is removed because it is not needed any more.
> - `NativeCall::trampoline_jump`:
>     - Changed to return `void` because the result is not used. It was returning the result of `emit_trampoline_stub`.
>     - Assert `emit_trampoline_stub`.
> 
> Tested with fastdebug/release builds:
> - `gtest`: Passed.
> - `tier1`...`tier4`: Passed.

Evgeny Astigeevich has updated the pull request incrementally with three additional commits since the last revision:

 - Restore original NativeCall::trampoline_jump functionality
 - Substitute entry.target() with target
 - Remove unneeded assert

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9782/files
  - new: https://git.openjdk.org/jdk/pull/9782/files/ab81d0b2..2e5e4aee

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9782&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9782&range=00-01

  Stats: 10 lines in 3 files changed: 3 ins; 1 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/9782.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9782/head:pull/9782

PR: https://git.openjdk.org/jdk/pull/9782