[OpaquePtr][BitcodeWriter] Handle attributes with types

For example, byval.

Skip the type attribute auto-upgrade if we already have the type.

I've actually seen this error of the ValueEnumerator missing a type
attribute's type in a non-opaque pointer context.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D105138

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -3333,6 +3333,9 @@ Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {
       if (!Func->hasParamAttribute(i, Kind))
         continue;
 
+      if (Func->getParamAttribute(i, Kind).getValueAsType())
+        continue;
+
       Func->removeParamAttr(i, Kind);
 
       Type *PTy = cast<FunctionType>(FTy)->getParamType(i);