Only _WIN32 is defined by the compiler, and WIN32 is not standardized
and may be missing.

Closes #169

Fixes the non-Linux build.

Enforcing MADV_DONTFORK is a surprising limitation for this library
which aims to be generic.

Without MEM_COMMIT, the reserved address space is not accessible, and
MPD crashes.

MEM_LARGE_PAGES does not appear to work.  Instead, MEM_RESERVE appears
to be necessary.  Until I figure this out, this large pages are
disabled.