Fix Misc.canonicalize_filename
Fix Misc.canonicalize_filename

Previous implementation was failing to go back to parent directories

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