If a file previously was generated but now isn't (ie. its .do file
disappears), we would never re-stamp that target, and so all its
dependencies would rebuild continually.
We had a bug (fixed in the previous commit) where doing 'redo-ifchange
dirname' (which runs dirname/all.do) would not create the stamp correctly,
so that it would always show up as dirty.
It's a little bit complicated to simulate, but this does it.
Unfortunately it failed before the previous patch, so that's why this test
is needed :(
The test is a little ugly, because the bug I'm testing for didn't happen
except if you ran 'redo' two times in a row, not two times inside the same
redo session. That's because dependency caching inside the one session
prevents the accidental rebuild.
.do files should never modify $1, and should write to *either* $3 or stdout,
but not both. If they write to both, it's probably because they forgot to
redirect stdout to stderr, a very easy mistake to make but a hard one to
detect.
Now redo detects it for you and prints an informative message.
Now 'redo test' runs the tests, but 'redo t' just builds the programs.
Also removed wvtest stuff; we're not really using it properly anyway and
it's not helping our testing right now. It might come back later.
