ocfs2: make local header paths relative to C files

Gang He reports the failure of building fs/ocfs2/ as an external module
of the kernel installed on the system:

 $ cd fs/ocfs2
 $ make -C /lib/modules/`uname -r`/build M=`pwd` modules

If you want to make it work reliably, I'd recommend to remove ccflags-y
from the Makefiles, and to make header paths relative to the C files.  I
think this is the correct usage of the #include "..." directive.

Link: http://lkml.kernel.org/r/20191227022950.14804-1-ghe@suse.com
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Gang He <ghe@suse.com>
Reported-by: Gang He <ghe@suse.com>
Reviewed-by: Gang He <ghe@suse.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>