LLVM IR: Generate new-style byval-with-Type from Clang

LLVM IR recently added a Type parameter to the byval Attribute, so that
when pointers become opaque and no longer have an element type the
information will still be present in IR.

For now the Type parameter is optional (which is why Clang didn't need
this change at the time), but it will become mandatory soon.

llvm-svn: 362652