Fixes type of dyldInfo for glibc/bionic systems

Darwin and the BSDs define a tagged struct dl_info typedef'd as Dl_info. glibc
and bionic typedef an anonymous struct as Dl_info.


git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@206939 91177308-0d34-0410-b5e6-96231b3b80d8