[LLVM] Accept noundef attribute in function definitions/calls

The `noundef` attribute indicates an argument or return value which
may never have an undef value representation.

This patch allows LLVM to parse the attribute.

Differential Revision: https://reviews.llvm.org/D83412

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -1530,6 +1530,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::SanitizeMemTag;
   case bitc::ATTR_KIND_PREALLOCATED:
     return Attribute::Preallocated;
+  case bitc::ATTR_KIND_NOUNDEF:
+    return Attribute::NoUndef;
   }
 }