lib: test_bitmap: add more start-end:offset/len tests

There are inputs to bitmap_parselist() that would probably never
be entered manually by a person, but might result from some kind of
automated input generator.  Things like ranges of length 1, or group
lengths longer than nbits, overlaps, or offsets of zero.

Adding these tests serve two purposes:

1) document what might seem odd but nonetheless valid input.

2) don't regress from what we currently accept as valid.

Cc: Yury Norov <yury.norov@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>