fts: bug fixes

[Jim Meyering]

This propagates a change from coreutils and
also fixes a typo in fts.m4:

diff --git a/lib/fts.c b/lib/fts.c
index 95d0c7a..a55a98d 100644
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -934,8 +934,8 @@ fts_children (register FTS *sp, int instr)
        return (sp->fts_child);
 }

-#if defined HAVE_SYS_VFS_H && HAVE_FSTATFS && HAVE_STRUCT_STATFS_F_TYPE
-# include <sys/statfs.h>
+#if HAVE_SYS_VFS_H && HAVE_FSTATFS && HAVE_STRUCT_STATFS_F_TYPE
+# include <sys/vfs.h>
 /* FIXME: what about when f_type is not an integral type?
    deal with that if/when it's encountered.  */
 static bool
diff --git a/m4/fts.m4 b/m4/fts.m4
index bdba388..2cc9d98 100644
--- a/m4/fts.m4
+++ b/m4/fts.m4
@@ -1,4 +1,4 @@
-#serial 15
+#serial 16
 dnl Copyright (C) 2005-2008 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -24,7 +24,7 @@ AC_DEFUN([gl_FUNC_FTS_CORE],
   gl_FUNC_OPENAT

   AC_CHECK_FUNCS_ONCE([fstatfs])
-  AC_CHECK_HEADERS_ONCE([sys/param.h sys/vfs])dnl
+  AC_CHECK_HEADERS_ONCE([sys/param.h sys/vfs.h])dnl
   AC_CHECK_MEMBERS([struct statfs.f_type],,,
     [$ac_includes_default
      #include <sys/statfs.h>])