Add OS_PATH_SEPARATOR for platforms which have different path separator characters (e.g. Windows and 'classic' MacOS).

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/filesetup.c b/filesetup.c
index d55af45..cf5ec8e 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -1138,7 +1138,7 @@
 		if (!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, ".."))
 			continue;
 
-		sprintf(full_path, "%s/%s", dirname, dir->d_name);
+		sprintf(full_path, "%s%s%s", dirname, FIO_OS_PATH_SEPARATOR, dir->d_name);
 
 		if (lstat(full_path, &sb) == -1) {
 			if (errno != ENOENT) {