-Make sure that a deserialized external decl gets added to the TU scope.
-When associating an identifier with a set of decls, use the most recent local ones,
if they exist, otherwise associating decls from modules (that came after a local one)
will lead to an incomplete reconstructed re-declaration chain.
rdar://13712705
llvm-svn: 180634
Argyrios Kyrtzidis