lib: add module support to array-based sort tests

Allow to compile the array-based sort test code either to a loadable
module, or builtin into the kernel.

Link: http://lkml.kernel.org/r/1488287219-15832-3-git-send-email-geert@linux-m68k.org


Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>