clients of the Deserializer to read the pointer ID before they are ready
to deserialize the object (which can mean registering a pointer reference
with the backpatcher).
Changed some methods that took an argument "SerializedPtrID" to "const SerializedPtrID&" (pass-by-reference). This is to accommodate a future
revision of SerializedPtrID where it may be much fatter than an unsigned
integer.
llvm-svn: 44021