Revert "[libc++] Take 2: Do not cleverly link against libc++abi just because it happens to be there"

r365326 still breaks bots:
http://lab.llvm.org:8011/builders/netbsd-amd64/builds/20712/steps/ninja%20build%20local/logs/stdio
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-autoconf/builds/39477/steps/test%20tsan%20in%20debug%20compiler-rt%20build/logs/stdio

And probably others

This reverts commit 945b9ec0693390ef35fe8c6b774495312246b8b6.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@365359 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed