Change FLAG(x) macros to always return 0 or 1. Treewide audit of FLAG()

users to make sure nobody NEEDED FLAG(x) to return the masked bit value,
and to remove now-redundant !!, with a number of in-passing cleanups
while I was there.

I think I fixed an actual bug in patch.c (-R depended on the flag value
but commit 6f6b7614e463 changed it, so "+-"[FLAG(R)] was comparing
against the NUL terminator when measuring fuzz) but we didn't have a
test for "fuzz autodetection". And there was another bug in tar.c
where DIRTREE_BREADTH was assigned to a local variable... and then not
used. But the test passed? (Not sure the flag's needed at the top level,
added a comment to the test suite to remind me to revisit that.)

While I was there, capitalize TODO comments so they're easier to grep for.

1 files changed, 2 insertions, 3 deletions

diff --git a/toys/posix/du.c b/toys/posix/du.c
index 05dea096..8bf9575d 100644
--- a/toys/posix/du.c
+++ b/toys/posix/du.c
@@ -114,8 +114,7 @@ static int do_du(struct dirtree *node)
   else if (!dirtree_notdotdot(node)) return 0;
 
   // detect swiching filesystems
-  if (FLAG(x) && (TT.st_dev != node->st.st_dev))
-    return 0;
+  if (FLAG(x) && TT.st_dev != node->st.st_dev) return 0;
 
   // Don't loop endlessly on recursive directory symlink
   if (FLAG(L)) {
@@ -132,7 +131,7 @@ static int do_du(struct dirtree *node)
   if (S_ISDIR(node->st.st_mode)) {
     if (!node->again) {
       TT.depth++;
-      return DIRTREE_COMEAGAIN|(DIRTREE_SYMFOLLOW*!!FLAG(L));
+      return DIRTREE_COMEAGAIN|DIRTREE_SYMFOLLOW*FLAG(L);
     } else TT.depth--;
   }