/usr/bin/i686-w64-mingw32-ocamlmktop is in ocaml-mingw-w64-i686 4.01.0~20140328-1build3.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | #!/bin/sh
#########################################################################
#                                                                       #
#                                 OCaml                                 #
#                                                                       #
#            Damien Doligez, projet Para, INRIA Rocquencourt            #
#                                                                       #
#   Copyright 1999 Institut National de Recherche en Informatique et    #
#   en Automatique.  All rights reserved.  This file is distributed     #
#   under the terms of the Q Public License version 1.0.                #
#                                                                       #
#########################################################################
exec /usr/i686-w64-mingw32/bin/ocamlc -I +compiler-libs -linkall ocamlcommon.cma \
                       ocamlbytecomp.cma ocamltoplevel.cma "$@" topstart.cmo
 |