RFR (XS) 8059474: Clean up vm/utilities/Bitmap type uses

[Aleksey Shipilev]

Hi,

Not sure which group this belongs to, using the generic hotspot-dev at .

vm/utilities/BitMap inconsistencies bugged me for quite some time: the
mention of naked uintptr_t instead of properly typedef-ed bm_word_t
alias; casting AllBits/NoBits constants of (luckily) the same type;
other things like a benign inconsistency in init_pop_count_table
new/free, etc.

Here is a cleanup, please review:
  http://cr.openjdk.java.net/~shade/8059474/webrev.00/
  https://bugs.openjdk.java.net/browse/JDK-8059474

Testing:
  JPRT, Nashorn/Octane on Linux/x86_64/fastdebug.

Thanks,
-Aleksey.