RFR: 8256594: Unexpected warning: SIGSEGV handler flags expected:SA_RESTART|SA_SIGINFO found:SA_RESTART|SA_SIGINFO [v2]

[David Holmes]

> In the recent POSIX signal code cleanup (JDK-8253742) I misunderstood the role of the SIGNIFICANT_SIGNAL_MASK and removing its application causes -Xcheck:jni to report errors with the signal handler due to an unexpected bit in the sigaction.sa_flags field.
> 
> This fix restores the masking of that flag, for Linux only, and more clearly indicating what it is. I also augmented the flag printing code to show when an unexpected flag is present (and so avoid the mysterious "expected X found X" message).
> 
> See bug report for more details.
> 
> Thanks.

David Holmes has updated the pull request incrementally with one additional commit since the last revision:

  Added missing mask of VMError::get_resetted_sigflags(sig)

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1309/files
  - new: https://git.openjdk.java.net/jdk/pull/1309/files/50ae0847..f7626ba1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1309&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1309&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1309.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1309/head:pull/1309

PR: https://git.openjdk.java.net/jdk/pull/1309