IR: Make metadata typeless in assembly, clang side

Match LLVM changes from r224257.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@224259 91177308-0d34-0410-b5e6-96231b3b80d8
Update this testcase for the new metadata assembler syntax.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@224262 91177308-0d34-0410-b5e6-96231b3b80d8