kmemleak: free internal objects only if there're no leaks to be reported

Currently if you stop kmemleak thread before disabling kmemleak,
kmemleak objects will be freed and so you won't be able to check
previously reported leaks.

With this patch, kmemleak objects won't be freed if there're leaks that
can be reported.

Change-Id: I31c837fa63f99f65a553471de46729d8d8e08ed5
Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: dc9b3f424903f7d6992778b69b1e35d864914ae5
Git-repo: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/


Signed-off-by: Vignesh Radhakrishnan <vigneshr@codeaurora.org>