Remove a couple of unused variables in the C runtime.
Micro-optimize gc scavenge.

Instead of putting the amount by which to increment the pointer and
then adding it at the end of the loop, increment the pointer
directly. Makes it slightly faster when compiled with GCC.
slep-non-consing test: prevent from sleeping too much.

Some platforms can't sleep for short amounts of time, add a
sb-ext:with-timeout around it and don't report it as a failure, since
there's basically nothing that can be fixed in such cases.
Handle compiler-error in LOAD when it's not run from inside EVAL.

When LOAD is run from the --load option or from within a new thread,
it doesn't go though EVAL and doesn't inherit its compiler-error
handler.

Fixes lp#1219601.
Add SOCKET-SHUTDOWN in contrib/sb-bsd-sockets

* The new generic function SOCKET-SHUTDOWN shuts down a socket for
  input, output or both. Calls shutdown(3posix)

* Test shutdown.{client,server}.{ub8,character}.{output,io} test
  shutting down TCP stream sockets from the client and server side for
  different element-types and directions