RFR: 8265327: Remove check_safepoint_and_suspend_for_native_trans()

[Patricio Chilano Mateo]

Hi,

Please review this small fix. Method check_safepoint_and_suspend_for_native_trans() can just be removed and the code moved directly to check_special_condition_for_native_trans(). The other caller, transition_from_native(), can also just call SafepointMechanism::process_if_requested_with_exit_check() after transitioning to _thread_in_native_trans. Since that removes the only caller of is_suspend_after_native() I also removed it. 
I also made a small fix to has_special_runtime_exit_condition(). The compilers were generating three different comparisons for _suspend_flags instead of combining the constant values and doing a single one (I checked this with gcc 10.2 on linux and clang-12 on macos). The extra code was preventing inlining on some cases. For instance, on a Linux release build with gcc 10.2, for the ThreadInVMfromNative constructor, transition_from_native() was being inlined but not process_if_requested_with_exit_check(), so we still required a call for the fast case. The small change to has_special_runtime_exit_condition() fixed that. 
Tested in mach5 tiers1-2.

Thanks,

Patricio

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

Commit messages:
 - fix has_special_runtime_exit_condition() to favor inlining
 - remove is_suspend_after_native()
 - v1

Changes: https://git.openjdk.java.net/jdk/pull/3548/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3548&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265327
  Stats: 38 lines in 3 files changed: 6 ins; 25 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3548.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3548/head:pull/3548

PR: https://git.openjdk.java.net/jdk/pull/3548