[8u] Revert Shenandoah-specific assert after JDK-8211926 landed

[Roman Kennke]

Ok. Thanks!

Roman

> Shenandoah-specific assert is not needed anymore, after all relevant backports landed upstream. This
> reverts bitMap.inline.hpp to 8u upstream state.
> 
> diff -r 37c96d78c3c2 src/share/vm/utilities/bitMap.inline.hpp
> --- a/src/share/vm/utilities/bitMap.inline.hpp  Wed Jul 17 18:09:43 2019 +0200
> +++ b/src/share/vm/utilities/bitMap.inline.hpp  Thu Jul 18 18:22:04 2019 +0200
> @@ -322,10 +322,10 @@
> 
>  inline void BitMap::set_large_range_of_words(idx_t beg, idx_t end) {
> -  assert(!UseShenandoahGC || (beg <= end), "underflow"); // Make sure Shenandoah does not blow up
> on JDK-8211926
> +  assert(beg <= end, "underflow");
>    memset(_map + beg, ~(unsigned char)0, (end - beg) * sizeof(uintptr_t));
>  }
> 
>  inline void BitMap::clear_large_range_of_words(idx_t beg, idx_t end) {
> -  assert(!UseShenandoahGC || (beg <= end), "underflow"); // Make sure Shenandoah does not blow up
> on JDK-8211926
> +  assert(beg <= end, "underflow");
>    memset(_map + beg, 0, (end - beg) * sizeof(uintptr_t));
>  }
> 
> Testing: hotspot_gc_shenandoah
> 
> Thanks,
> -Aleksey
>