RFR: 8296270: Memory leak in ClassLoader::setup_bootstrap_search_path_impl

[Man Cao]

Hi all,

Could anyone help review this fix for a memory leak? There is a redundant code branch in ClassLoader::setup_bootstrap_search_path_impl() for exploded-image build that is unnecessary and causes a leak.

I'm sponsoring colleague Justin King (jcking at google.com) for this contribution, who remarkably made LeakSanitizer working for HotSpot and found this leak.

@jianglizhou also helped validate this fix. Quoting her comment:
> For the ClassPathEntry* new_entry = create_class_path_entry(current, path, &st, false, false); else case with an exploded build in jdk head codebase, it does appear to be not needed. It only creates the class path entry for <path>/modules/java.base, which is handled by [ClassLoader::add_to_exploded_build_list](http://google3/third_party/java_src/jdk/head/src/src/hotspot/share/classfile/classLoader.cpp;l=671;rcl=478881875) later again. Just to be sure, I checked in lldb. The <path>/modules/java.base module path entry is created twice.

-Man

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

Commit messages:
 - 8296270: Memory leak in ClassLoader::setup_bootstrap_search_path_impl

Changes: https://git.openjdk.org/jdk/pull/10973/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10973&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296270
  Stats: 4 lines in 1 file changed: 0 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10973.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10973/head:pull/10973

PR: https://git.openjdk.org/jdk/pull/10973