Enabled with 'let g:syntastic_ocaml_use_ocamlbuild = 1' in .vimrc,
also creates .annot files for <Leader>t.
Not enabled by default because it writes to disk (_build dir).
Move the locaml->lcaml alias function out of the ocaml checker as this
code wont be loaded for locaml files - only syntax checkers for filetype
that are in use get sourced