helper/list: include the correct header file
The file 'list.h', copied from FreeBSD, does not depend from any
OpenOCD specific include file, but only needs 'stddef.h' for the
type 'size_t'.
Let 'list.h' to include the correct header file, then fix the now
broken dependencies in the other files that were incorrectly
relying on 'list.h' to include 'helper/types.h'
Change-Id: Idd31b5bf607e226cac44ef41b2aa335ae4dbf519
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8173
Tested-by: jenkins