scripts: Re-adopted result prefixes

Now that I'm looking into some higher-level scripts, being able to merge
results without first renaming everything is useful.

This gives most scripts an implicit prefix for field fields, but _not_
by fields, allowing easy merging of results from different scripts:

  $ ./scripts/stack.py lfs.ci -o-
  function,stack_frame,stack_limit
  lfs_alloc,288,1328
  lfs_alloc_discard,8,8
  lfs_alloc_findfree,16,32
  ...

At least now these have better support in scripts with the addition of
the --prefix flag (this was tricky for csv.py), which allows explicit
control over field field prefixes:

  $ ./scripts/stack.py lfs.ci -o- --prefix=
  function,frame,limit
  lfs_alloc,288,1328
  lfs_alloc_discard,8,8
  lfs_alloc_findfree,16,32
  ...

  $ ./scripts/stack.py lfs.ci -o- --prefix=wonky_
  function,wonky_frame,wonky_limit
  lfs_alloc,288,1328
  lfs_alloc_discard,8,8
  lfs_alloc_findfree,16,32
  ...

scripts/test.py

@@ -1099,8 +1099,8 @@ def run_stage(name, runner, test_ids, stdout_, trace_, output_, **args):
                                     'suite': suite,
                                     'case': case,
                                     **defines,
-                                    'passed': '1/1',
-                                    'time': '%.6f' % (
+                                    'test_passed': '1/1',
+                                    'test_time': '%.6f' % (
                                         time.time() - last_time)})
                     elif op == 'skipped':
                         locals.seen_perms += 1
@@ -1161,7 +1161,7 @@ def run_stage(name, runner, test_ids, stdout_, trace_, output_, **args):
                     output_.writerow({
                             'suite': suite,
                             'case': case,
-                            'passed': '0/1',
+                            'test_passed': '0/1',
                             **defines})
 
                 # race condition for multiple failures?
@@ -1297,7 +1297,8 @@ def run(runner, test_ids=[], **args):
     if args.get('output'):
         output = TestOutput(args['output'],
                 ['suite', 'case'],
-                ['passed', 'time'])
+                # defines go here
+                ['test_passed', 'test_time'])
 
     # measure runtime
     start = time.time()