RFR: JDK-8301354: Modernize utilities/breakpoint.hpp [v2]

[Justin King]

> Cleanup `utilities/breakpoint.hpp` by utilizing compiler intrinsics when available, or normal signals for AIX/XLC.

Justin King has updated the pull request incrementally with one additional commit since the last revision:

  Update GCC to use __builtin_trap as a fallback
  
  Signed-off-by: Justin King <jcking at google.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12296/files
  - new: https://git.openjdk.org/jdk/pull/12296/files/de6daca0..af4bef60

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12296&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12296&range=00-01

  Stats: 8 lines in 1 file changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12296.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12296/head:pull/12296

PR: https://git.openjdk.org/jdk/pull/12296