Make the AttrListPtr object a part of the LLVMContext.

When code deletes the context, the AttributeImpls that the AttrListPtr points to
are now invalid. Therefore, instead of keeping a separate managed static for the
AttrListPtrs that's reference counted, move it into the LLVMContext and delete
it when deleting the AttributeImpls.

llvm-svn: 168354

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -487,7 +487,7 @@ bool BitcodeReader::ParseAttributeBlock() {
                                                   Attributes::get(Context, B)));
       }
 
-      MAttributes.push_back(AttrListPtr::get(Attrs));
+      MAttributes.push_back(AttrListPtr::get(Context, Attrs));
       Attrs.clear();
       break;
     }