dejagnu(1) multi-launcher and dejagnu-report-card

The discussion that started with fixing a nasty bug in MULTIPASS veered 
(at 
<URL:http://lists.gnu.org/archive/html/bug-dejagnu/2018-11/msg00010.html>) 
into improving the DejaGnu testsuite and adding a summarization tool, so 
that the overall results of DejaGnu runs testing multiple tools can be 
reported in a nice table.  I was asked to move the discussion to the 
main dejagnu list, so am reproposing this here.

First, add a new dejagnu(1) multi-purpose launcher, in a style similar 
to git(1).  This allows to select at run-time between multiple versions 
of auxiliary tools, depending on what is available on the system.  This 
leads to a slightly more complex "structure" for DejaGnu, with an "inner 
core" (runtest(1) and its components) and an "outer core" (the 
dejagnu(1) subcommands) that is also installed. One of the reasons for 
this is that I would like the DejaGnu testsuite itself to use the 
dejagnu-report-card tool, and possibly for a future version of Automake 
to use it if the DEJATOOL variable indicates to test multiple tools.

Second, the first subcommand to implement would be "dejagnu 
report-card", for which I already have shell and Tcl implementations.  
This would then be usable as part of the DejaGnu testsuite to provide a 
nice summary at the end of a testsuite run.

Future plans include some kind of "canned test" feature to help with 
creating new testsuites and adding tools. Something like "dejagnu create 
testsuite" and "dejagnu add tool" would be nice.


-- Jacob