new mmap() module (for windows) and license choice

[Mike Frysinger]

i wrote a mmap/munmap replacement for windows for another project of mine 
after i got it working, i realized that ive used gnulib in quite a bit of 
things and it kind of sucks that there is no mmap module already.  so i looked 
at contributing it to gnulib and had some questions regarding 
copyright/licensing.

i wrote this module from scratch (all puny ~90 lines) using the POSIX/MS API 
documentation and placed it into the public domain.  i see there are a few 
modules that also use public domain licensing, but the toplevel README wording 
seems to kind of discourage this kind of thing.  so is this possible ?
-mike