t/*: some cleanups so switching between redo and minimal/do works.

Because the two programs use separate state databases, it helps if we
clean up some temp files between runs.  Otherwise they might think you
created some targets "by hand" and refuse to rebuild them.

t/360-symlinks/all.do

@@ -11,6 +11,8 @@ redo-ifchange b
 d2=$(cat b.did)
 [ "$d1" = "$d2" ] || exit 12
 
+. ../skip-if-minimal-do.sh
+
 # forcibly changing a should rebuild b.
 # a is already symlink to a.extra, but redo shouldn't care about the
 # target of symlinks, so it shouldn't freak out that a.extra has changed.