unwind: permit building against libstdc++
unwind: permit building against libstdc++

Include algorithm early as otherwise you get a number of particularly unhelpful
messages about failed static assertions.  This fixes compilation on Linux with
gcc.

git-svn-id: 62ef012455b6b8fcec9c41ca270ebf409aae1006@237002 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/libunwind,llvm-mirror/libunwind,llvm-mirror/libunwind