locate: fix constructors and label lookup
locate: fix constructors and label lookup

dra27/merlin,neojski/merlin,neojski/merlin,rgrinberg/merlin,rgrinberg/merlin,dra27/merlin,the-lambda-church/merlin,haselwarter/merlin,chriskonstad/merlin,chambart/merlin,chambart/merlin,the-lambda-church/merlin,chambart/merlin,haselwarter/merlin,dra27/merlin,neojski/merlin,fxfactorial/merlin,chriskonstad/merlin,chambart/merlin,neojski/merlin,haselwarter/merlin,rgrinberg/merlin,fxfactorial/merlin,ocaml/merlin,the-lambda-church/merlin,fxfactorial/merlin,fxfactorial/merlin,dra27/merlin,rgrinberg/merlin,ocaml/merlin,ocaml/merlin,ocaml/merlin,haselwarter/merlin