mm,kmemleak-test.c: move kmemleak-test.c to samples dir

mm,kmemleak-test.c: move kmemleak-test.c to samples dir

kmemleak-test.c is just a kmemleak test module, which also can not be used
as a built-in kernel module.  Thus, i think it may should not be in mm
dir, and move the kmemleak-test.c to samples/kmemleak/kmemleak-test.c.
Fix the spelling of built-in by the way.

Signed-off-by: Hui Su <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Divya Indi <[email protected]>
Cc: Tomas Winkler <[email protected]>
Cc: David Howells <[email protected]>
Link: https://lkml.kernel.org/r/20200925183729.GA172837@rlk
Signed-off-by: Linus Torvalds <[email protected]>