Justification for separate ${tool}-dg.exp

[Rainer Orth]

While reviewing the GCC testsuite, I noticed that practically every
testsuite driver has the equivalent of

load_lib ${tool}-dg.exp

While ${tool}.exp is automatically loaded by the framework, this file
needs to be loaded separately.

It is sort of documented in dg.exp:

# The normal way to write a testsuite is to have a .exp file containing:
#
# load_lib ${tool}-dg.exp
# dg-init
# dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/foo*]] ...
# dg-finish

but so far I've no idea what the point is and how to decide what goes
into ${tool}.exp and what into ${tool}-dg.exp.  Unless there is a good
reason for this separation, I plan to go over the GCC testsuites and
remove the explicit load_lib and do that in the corresponding
${tool}.exp until both are merged.

Comments?

        Rainer

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Rainer Orth, Center for Biotechnology, Bielefeld University