Fix off-by-one.

Hiss!

Unlike the rest of the memory-mode enum, this one didn't only
describe the access mode of the input memory region.  Remove it.

If someone wants to inhibit duplicating, they can lock the blob
and throw away the key.

Based on mailing list discussion with Carl Worth.

Autoconfiscate a simple call to mprotect() even more.

Bug 592036 - integer overflow bug causes misrendering of Nepali characters

Fix the second instance.

Check for sys/mman.h, not mprotect().

Bit field packing is a delicate field.  Issue reported in comment 3 here:
http://bugzilla.gnome.org/show_bug.cgi?id=591511

Enforce -fno-exceptions better.

Only call mprotect() when available.  For optimal performance, a win32
way to make memory writeable needs to be added.