RFR: 8351309: test/hotspot/jtreg/runtime/posixSig/TestPosixSig.java fails on static-jdk [v2]

[Jiangli Zhou]

> Please review this PR that excludes `libjsig` from being statically linked with `static-jdk` `java` launcher by default. Please see details in https://bugs.openjdk.org/browse/JDK-8351309 description and comments. Thanks

Jiangli Zhou has updated the pull request incrementally with two additional commits since the last revision:

 - Address magicus' feedback, set `ONLY_EXPORTED := true` for LIBJSIG.
 - Revert make/StaticLibs.gmk.

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/23924/files
  - new: https://git.openjdk.org/jdk/pull/23924/files/9e1aac2e..9419b7f1

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23924&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23924&range=00-01

  Stats: 8 lines in 2 files changed: 1 ins; 6 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23924.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23924/head:pull/23924

PR: https://git.openjdk.org/jdk/pull/23924