Fix typo in comment
The hcoll component configure.m4 commits multiple sins, and breaks
many builds.  I am temporarily .ompi_ignore'ing this component until
it can be fixed by its owner.

 * It calls AC_MSG_ERROR, which configure.m4 scripts are ''never''
   supposed to do.  If you don't want to build, then call $2.
 * All static and --disable-dlopen builds are broken; they fall afoul
   of whatever test configure.m4 is doing and therefore error out of
   configure entirely (vs. simply disabling the hcoll component).
 * There appear to be multiple shell scripting errors in the
   configure.m4.  Here's the output of "./configure --disable-dlopen":
{{{
--- MCA component coll:hcoll (m4 configuration macro)
checking for MCA component coll:hcoll compile mode... static
checking --with-hcoll value... simple ok (unspecified)
./configure: line 421: test: basic: integer expression expected
configure: error: Can not use coll/hcoll and coll/ml (static build)
   simultaneously. You have two options:
                1. Use static build & disable ml with:
   --enable-mpi-no-build=coll-ml
                2. Use dso build for ML & disable ml at runtime: -mca
   coll self
./configure: line 310: return: basic: numeric argument required
./configure: line 320: exit: basic: numeric argument required
}}}

Finally, all of these configure.m4 errors aside, I don't understand
why there is a ''compile-time'' exclusion between the hcoll and ml
components.  Why isn't this a ''run-time'' decision?  Having what
seems to be an unnecessary compile-time exclusion goes against the
general Open MPI philosophy.

Note: Open MPI 1.7 is also broken in all the same ways.  I suggest
that the RM's .ompi_ignore hcoll over there, too.

Mellanox: please fix.