clean: simplify dir/not-dir logic

When we get a list of paths from read_directory, we further
prune it to create the final list of items to remove. The
code paths for directories and non-directories repeat the
same "add to list" code.

This patch restructures the code so that we don't repeat
ourselves. Also, by following a "if (condition) continue"
pattern like the pathspec check above, it makes it more
obvious that the conditional is about excluding directories
under certain circumstances.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/clean.c

@@ -967,15 +967,12 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 		if (pathspec.nr && !matches)
 			continue;
 
-		if (S_ISDIR(st.st_mode)) {
-			if (remove_directories || (matches == MATCHED_EXACTLY)) {
-				rel = relative_path(ent->name, prefix, &buf);
-				string_list_append(&del_list, rel);
-			}
-		} else {
-			rel = relative_path(ent->name, prefix, &buf);
-			string_list_append(&del_list, rel);
-		}
+		if (S_ISDIR(st.st_mode) && !remove_directories &&
+		    matches != MATCHED_EXACTLY)
+			continue;
+
+		rel = relative_path(ent->name, prefix, &buf);
+		string_list_append(&del_list, rel);
 	}
 
 	if (interactive && del_list.nr > 0)