Currently sym_check almost all names found in the binary, including those which are defined in other libraries. This makes our ABI lists harder to maintain. This patch adds a --only-stdlib-symbols option to sym_check which removes all symbols which aren't possibly provided by libc++. It also re-generates the linux ABI list after making this change. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@287294 91177308-0d34-0410-b5e6-96231b3b80d8