[libcxx] Move to using libc++abi2.exp as the default symbol list for libc++

Summary:
libc++abi2.exp should be used whenever `cxxabi.h` defines `_LIBCPPABI_VERSION`. This macro was added to libc++abi in 2012 in r149632. For this reason we should use libc++abi2.exp as default unless otherwise specified.

Also when building against an in-tree libc++abi we definitely want to use libc++abi2.exp.

I would love to know what OSX was the last to use libc++abi.exp but I can only test on 10.9.


Reviewers: danalbert, mclow.lists, EricWF

Reviewed By: EricWF

Subscribers: meadori, cfe-commits

Differential Revision: http://reviews.llvm.org/D7773

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@230119 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/test/config.py

@@ -439,7 +439,10 @@ class Configuration(object):
         elif cxx_abi == 'libsupc++':
             self.cxx.link_flags += ['-lsupc++']
         elif cxx_abi == 'libcxxabi':
-            self.cxx.link_flags += ['-lc++abi']
+            # Don't link libc++abi explicitly on OS X because the symbols
+            # should be available in libc++ directly.
+            if self.target_info.platform() != 'darwin':
+                self.cxx.link_flags += ['-lc++abi']
         elif cxx_abi == 'libcxxrt':
             self.cxx.link_flags += ['-lcxxrt']
         elif cxx_abi == 'none':