Revert "modpost: explain why we can't use strsep"

hulk inclusion
category: bugfix
bugzilla: 46847
CVE: NA

-----------------------------------------------

This reverts commit bd34c7e237442f10576363ea3515da4aca39baf1.

This series of patches could raise an issue on module built.

When we build a module that contains .cpp source file, we could only
build the corresponding object file by calling gcc emplicitly instead of
using the kbuild framework supplied by kernel. As a consequence, the
.cmd file that records the build command for the object file goes
missing.

This patches series treat that missing .cmd file as a fatal error and
break the module build. Although linking a object file supplied by user
into a module is informal, the user has already done that and we'd
better not break it for compatibility.

Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com>
Reviewed-by: Jian Cheng <cj.chengjian@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>