>So, yesterday I managed to get the tools finally building on a Mac OS X
>host.

Cool.

>My patch only eliminates the former; command line settings of variables
>still override settings in the Makefile (which is required for proper
>operation when e.g. building the tools).

The patch to make looks reasonable, though is it worth burning an option
char (must be running low ;-) an environment variable would do just
as well? ie.  MAKE_NO_EXPORT_VARS_TO_ENV_BECAUSE_IM_LAME ?

>Note that I'm not entirely happy with the patch to build.sh; the -X is only
>necessary when building in src/tools, so if someone could clue me in how to
>set the flag when we descend into src/tools or when we build from there
>directly, that'd be keen.

You can add something to the command line given to sub-makes using

.MAKEFLAGS+= -X


--sjg