Linking against libstdc++, rather than libsupc++, is probably better
for people who need to link against clients of libstdc++. Because
libsupc++ is provided only as a static library, its globals are not
shared between the static library and the copy linked into libstdc++.
This has been found to cause at least one test failure.
This also removes a number of symbols which were multiply defined
between libstdc++ and libc++, only when linking with libstdc++.
Differential Revision: http://llvm-reviews.chandlerc.com/D1825
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@192075 91177308-0d34-0410-b5e6-96231b3b80d8
