[jdk15u-dev] RFR: 8257467: [TESTBUG] -Wdeprecated-declarations is reported at sigset() in exesigtest.c

[Yuri Nesterenko]

clean backport; gcc 10 with libc 2.34 builds test-image OK.

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Commit messages:
 - Backport fb139cff1a6ddf7659908053d5a0a6ae7563e725

Changes: https://git.openjdk.org/jdk15u-dev/pull/275/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk15u-dev&pr=275&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8257467
  Stats: 8 lines in 1 file changed: 7 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk15u-dev/pull/275.diff
  Fetch: git fetch https://git.openjdk.org/jdk15u-dev pull/275/head:pull/275

PR: https://git.openjdk.org/jdk15u-dev/pull/275