RFR: 8328146: Set LIBCXX automatically [v3]

[Magnus Ihse Bursie]

> We are adding LIBCXX to LIBS in calls to SetupJdkLibrary whenever LINK_TYPE is C++. We should do this automatically in SetupJdkLibrary for C++ linking.
> 
> I also removed the superfluous `-lc` from some places where it had been added.

Magnus Ihse Bursie has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'master' into set-libcxx-automatically
 - Fix extra space
 - Restore $(LIBCXX) in tests since they don't use SetupJdkLibrary.
 - 8328146: Set LIBCXX automatically

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18298/files
  - new: https://git.openjdk.org/jdk/pull/18298/files/d7efdeaf..447e91eb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18298&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18298&range=01-02

  Stats: 1513 lines in 54 files changed: 1090 ins; 223 del; 200 mod
  Patch: https://git.openjdk.org/jdk/pull/18298.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18298/head:pull/18298

PR: https://git.openjdk.org/jdk/pull/18298