selftests/vm: add script helper for CONFIG_TEST_VMALLOC_MODULE

Add the test script for the kernel test driver to analyse vmalloc
allocator for benchmarking and stressing purposes.  It is just a kernel
module loader.  You can specify and pass different parameters in order
to investigate allocations behaviour.  See "usage" output for more
details.

Also add basic vmalloc smoke test to the "run_vmtests" suite.

Link: http://lkml.kernel.org/r/20190103142108.20744-4-urezki@gmail.com


Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Shuah Khan <shuah@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>