XFAIL elf/demangle.test on Windows.

Because LLD on that platform can't demangle symbols.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@221504 91177308-0d34-0410-b5e6-96231b3b80d8
Add missing -target triple to ELF tests.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@221505 91177308-0d34-0410-b5e6-96231b3b80d8