[11u] RFR: JDK-8256287: [windows] add loop fuse to map_or_reserve_memory_aligned

[Thomas Stüfe]

Hi,

may I please have reviews for the following downport:

Original issue: https://bugs.openjdk.java.net/browse/JDK-8256287
Original patch: https://github.com/openjdk/jdk/commit/0357db35.diff
Modified patch:
http://cr.openjdk.java.net/~stuefe/webrevs/backports/8256287-windows-add-loop-fuse-to-map_or_reserve_memory_aligned-for-11.diff

The original patch does not apply cleanly since this function had been
heavily reworked. I rewrote it from scratch, but since the problem is
simple this should be simple to review.

Thanks, Thomas