Testsuite custom environment

[David Edelsohn]

>>>>> Janis Johnson writes:

Janis> I've tried lots of different ways to get a variable passed through to
Janis> the testing tools and haven't yet figured out how to do it.  For the
Janis> binary compatibility tests I gave up and had the Makefile write
Janis> particular variables to site.exp; ugly, but it did what I needed.  If
Janis> there's a better way to do this, I'd like to know about it, too, and
Janis> then we can fix the documentation.
 
Are

	--tool_opts

and 
	RUNTESTFLAGS=""

useful?

	--tool_opts can specify additional options that always are applied
to the commandline when invoking the tool, but not overriding existing
flags.

	RUNTESTFLAGS can specify those options in an environment variable,
e.g., when running from "make check".

David