yet another Makefile issue

[Matthew Fluet]

This one concerns /src/runtime/Makefile.

I was trying to get my remote build scripts to work on my home machine.
For some reason that I haven't figured out, /sbin ends up on my path when
I ssh into that machine.  This causes a problem with building the runtime,
in particular gmp.  It puts install-info in my path, which causes the
following rule in gmp-2.0.2/Makefile to have different behaviour:

install-info-files: installdirs $(srcdir)/gmp.info
	cd $(srcdir); for f in gmp.info*; \
	do $(INSTALL_DATA) $$f $(infodir)/$$f; done
	-chmod a-x $(infodir)/gmp.info*
	# Attempt to edit the info directory node
	if $(SHELL) -c 'install-info --version' >/dev/null 2>&1; then \
	  install-info --dir-file=$(infodir)/dir $(infodir)/gmp.info; \
	  else true; fi

(Every other machine I've run on, it seems that install-info isn't on my
path, so the if test fails and true is returned, and make continues as
normal.)  Somebody must have run into this before, because of the command

			echo 'a' | tr 'a' '\037' >gmp-stuff/info/dir && \

in the rule to make gmp.  Anyways, this doesn't seem to be a valid dir
file for info, the error I get is

install-info: runtime/gmp-stuff/info/dir: empty file

Things work out o.k. if I remove that command to make gmp-stuff/info/dir;
install-info just builds a dir file from scratch.

So, just wondering if anyone remembers why building a dummy dir file was
necessary.  And, if it doesn't seem to cause any other issues, I'll remove
that command.