RFR: 8282224: Correct TIG::bang_stack_shadow_pages comments

[Aleksey Shipilev]

When reviewing the RISC-V port of the change, I noticed the comment in the x86 code is worded incorrectly:


  // Record a new watermark, unless the update is above the safe limit.
  __ cmpptr(rsp, Address(thread, JavaThread::shadow_zone_safe_limit()));
  __ jccb(Assembler::belowEqual, L_done);


Stacks grow downwards, so we are recording a new watermark *when* update is above the safe limit.

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Commit messages:
 - Fix

Changes: https://git.openjdk.java.net/jdk/pull/7569/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7569&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282224
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7569.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7569/head:pull/7569

PR: https://git.openjdk.java.net/jdk/pull/7569