Set hint for invokespec and multispec.

Means the attribute lookups go a good amount faster.
Improve the VM exit strategy.

It now doesn't try to do all the cleanup work by default, instead
leaving it to the OS, which can no doubt do it faster. There is now
a --full-cleanup flag for requesting full cleanup, however. In either
case, special effort to gracefully join foreground threads is made,
so "Thread.start({ sleep 1; say 'bye' }); say 'hi'" in Perl 6 will now
output hi\nbye\n reliably (and passing :app_lifetime will not show the
bye\n, and seems to exit cleanly too provided --full-cleanup isn't
passed).
Unbreak CGOTO compilation.

It can't cope with ops in oplist but having no stub in interp.c.
Correctly handle temp roots stack in callbacks.
add sched_yield for NetBSD
Merge pull request #91 from stmuk/master

add sched_yield for NetBSD
Fix callsite size calculation in tweak_cs.

Avoids trying to access memory beyond its allocated boundary. Found by
nwc10++ using ASAN/Valgrind.
Fix buffer overflow in UTF-16 encoding.
Make sure is_interned is zeroed as needed.

Patch partially thanks to nwc10++ (the args.c case), who also found
the general issue. Other 3 changes are other places vulnerable to the
same kind of bug.
Trigger repossession on OP(push_o)
Trigger repossession on OP(push_*)
Merge pull request #92 from retupmoca/master

Trigger repossession on OP(push_*)
Fake up a final entry off the end of Unicode

This seems to fix the problems of undefined behavior in plane 16
discovered by lue++.