Fix bm_huge initialization for 64-bit targets (gctest)

Fix bm_huge initialization for 64-bit targets (gctest)

* tests/test.c (bm_huge): Make array size depend on word size
(5 elements for 64-bit targets); initialize elements (except the last
one) to -1 instead of 0xffffffff (so that all bits are ones even on
a 64-bit target); initialize last element to ((word)-1)>>8 instead of
0x00ffffff value.
* tests/test.c (typed_test): Fail if bm_huge descriptor contains wrong
bit values at certain positions (as it had before this fix).