`SystemLookup` in FFM uses libsyslookup to find symbols from the system. But it is not needed because `RTLD_DEFAULT` can be used for this purpose on Linux. Removing unneeded library improves security.
I've sent [email](https://mail.openjdk.org/archives/list/[email protected]/thread/KHXIJCQZD2VCY4QXMPONAPS26IERMEGR/) to core-libs-dev, but I've not yet received any comments, so I created this PR. syslookup.dll for Windows is needed because some functions might not be lookup'ed. OTOH on Linux, `dlsym` can lookup symbols from library dependencies. In `SystemLookup`, handle of libsyslookup would be passed to `dlsym` eventually, but it is better to pass `RTLD_DEFAULT` in this case. It works when the handle of libsyslookup is passed, but `RTLD_DEFAULT` is better because Javadoc of `Linker::defaultLookup` says it returns a set of commonly used libraries. In addition, I guess we can apply this change to all of POSIX platforms because `dlsym` is defined in POSIX, but I'm not sure we can do (especially AIX - it has own syslookup.c in JDK source tree). This change passed all of jdk_foreign tests. --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - Use RTLD_DEFAULT on Linux Changes: https://git.openjdk.org/jdk/pull/30794/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=30794&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8382428 Stats: 56 lines in 3 files changed: 40 ins; 1 del; 15 mod Patch: https://git.openjdk.org/jdk/pull/30794.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/30794/head:pull/30794 PR: https://git.openjdk.org/jdk/pull/30794
