scripts: Some csv script tweaks to better interact with other scripts

- Added --small-total. Like --small-header, this omits the first column
  which usually just has the informative text TOTAL.

- Tweaked -Q/--small-table so it renders with --small-total if
  -Y/--summary is provided.

- Added --total as an alias for --summary + --no-header + --small-total,
  i.e. printing only the totals (which may be multiple columns) and no
  other decoration.

  This is useful for scripting, now it's possible to extract just, say,
  the sum of some csv and embed with $():

    echo $(./scripts/code.py lfs3.o --total)

- Tweaked total to always output a number (0) instead of a dash (-),
  even if we have no results.

  This relies on Result() with no args, which risks breaking scripts
  where the Result type expects an argument. To hopefully catch this
  early, the table renderer currently creates a Result() before trying
  to fold the total result.

- If first column is empty (--small-total + --small-header, --no-header,
  etc) collapse width to zero. This avoids a bunch of extra whitespace,
  but still includes the two spaces normal used to separate names from
  fields.

  But I think those spaces are a good thing. It makes it hard to miss
  the implicit padding in the table renderer that risks breaking
  dependent scripts.

scripts/data.py

@@ -611,12 +611,28 @@ def table(Result, results, diff_results=None, *,
         no_header=False,
         small_header=False,
         no_total=False,
+        small_total=False,
         small_table=False,
         summary=False,
+        total=False,
         **_):
     import builtins
     all_, all = all, builtins.all
 
+    # small_table implies small_header + no_total or small_total
+    if small_table:
+        small_header = True
+        small_total = True
+        no_total = no_total or (not summary and not total)
+    # summary implies small_header
+    if summary:
+        small_header = True
+    # total implies summary + no_header + small_total
+    if total:
+        summary = True
+        no_header = True
+        small_total = True
+
     if by is None:
         by = Result._by
     if fields is None:
@@ -664,8 +680,7 @@ def table(Result, results, diff_results=None, *,
                             sum(1 for n in table if n not in diff_table),
                             sum(1 for n in diff_table if n not in table))
                         if diff_results is not None and not percent else '')
-                if not small_header and not small_table and not summary
-                    else '']
+                if not small_header else '']
         if diff_results is None or percent:
             for k in fields:
                 header.append(k)
@@ -861,13 +876,15 @@ def table(Result, results, diff_results=None, *,
         table_recurse(results, diff_results, depth)
 
     # total
-    if not no_total and not (small_table and not summary):
-        r = next(iter(fold(Result, results, by=[])), None)
+    if not no_total:
+        r = next(iter(fold(Result, results, by=[])), Result())
         if diff_results is None:
             diff_r = None
         else:
-            diff_r = next(iter(fold(Result, diff_results, by=[])), None)
-        lines.append(table_entry('TOTAL', r, diff_r))
+            diff_r = next(iter(fold(Result, diff_results, by=[])), Result())
+        lines.append(table_entry(
+                'TOTAL' if not small_total else '',
+                r, diff_r))
 
     # homogenize
     lines = [[x if isinstance(x, tuple) else (x, []) for x in line]
@@ -882,6 +899,8 @@ def table(Result, results, diff_results=None, *,
             widths[i] = max(widths[i], ((len(x[0])+1+4-1)//4)*4-1)
             if i != len(line)-1:
                 nwidths[i] = max(nwidths[i], 1+sum(2+len(n) for n in x[1]))
+    if not any(line[0][0] for line in lines):
+        widths[0] = 0
 
     # print our table
     for line in lines:
@@ -1202,14 +1221,23 @@ if __name__ == "__main__":
             '--no-total',
             action='store_true',
             help="Don't show the total.")
+    parser.add_argument(
+            '--small-total',
+            action='store_true',
+            help="Don't show TOTAL name.")
     parser.add_argument(
             '-Q', '--small-table',
             action='store_true',
-            help="Equivalent to --small-header + --no-total.")
+            help="Equivalent to --small-header + --no-total or --small-total.")
     parser.add_argument(
             '-Y', '--summary',
             action='store_true',
             help="Only show the total.")
+    parser.add_argument(
+            '--total',
+            action='store_true',
+            help="Equivalent to --summary + --no-header + --small-total. "
+                "Useful for scripting.")
     parser.add_argument(
             '--prefix',
             help="Prefix to use for fields in CSV/JSON output. Defaults "