RFR: 8285792: Posix signal handler modification checking issues. [v2]

[Harold Seigel]

> Please review this fix for JDK-8285792.  The fix removes print statements from check_signal_handler() so that it doesn't print all the handlers every time it finds one that is modified.  Instead, it returns true if the handler is modified, false otherwise.  Its caller, user_handler(), then prints all the handlers just once even if multiple signal handlers were modified.
> 
> The fix also adds a check for VMError::crash_handler_adress() to check_signal_handler() to prevent it from being treated as a signal handler modification.
> 
> The fix was tested with Mach5 tiers 1-2 on Linux and Mac OS and Mach 5 tiers 3-5 on Linux x64.  The regression test is excluded on Windows.
> 
> Thanks, Harold

Harold Seigel has updated the pull request incrementally with one additional commit since the last revision:

  Consolidate java test files, change tested signals

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9631/files
  - new: https://git.openjdk.org/jdk/pull/9631/files/c988e4d2..f57603ff

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9631&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9631&range=00-01

  Stats: 68 lines in 4 files changed: 13 ins; 39 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/9631.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9631/head:pull/9631

PR: https://git.openjdk.org/jdk/pull/9631