For PR1194:

The bcreader counts on "primitive" types being inserted before they are
referenced in other types. With recent changes to the bcwriter, this fact
became exposed since IntegerType is no longer "primitive". We can no longer
count on all IntegerTypes being inserted early. This patch modifies
getOrCreateTypeSlot to insert any sub-type that can't possibly recurse
before we create the slot for the type. This has the benefit of reducing
the number of OpaqueType objects the reader needs to deal with.

llvm-svn: 34147