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.

We were copying glyphs to output.  This should not happen when in
GPOS.  Back then it was fine, then some optimizations broke then
assumption.

Bug 591557 – [HB] crash scrolling the evolution message list
Bug 591576 – crashed with SIGSEGV at pango