Mega-merge of my last 2 weeks hacking.  This basically does the groundwork
for pthread_* support.  Major changes:

* Valgrind now contains a (skeletal!) user-space pthreads
  implementation.  The exciting bits are in new file vg_scheduler.c.
  This contains thread management and scheduling, including nasty crud
  to do with making some syscalls (read,write,nanosleep) nonblocking.
  Also implementation of pthread_ functions: create join
  mutex_{create,destroy,lock,unlock} and cancel.

* As a side effect of the above, major improvements to signal handling
  and to the client-request machinery.  This is now used to intercept
  malloc/free etc too; the hacky way this is done before is gone.
  Another side effect is that vg_dispatch.S is greatly simplified.
  Also, the horrible hacks to do with delivering signals to threads
  blocked in syscalls are gone, since the new mechanisms cover this case
  easily.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@52 a5019735-40e9-0310-863c-91ae7b9d1cf9
48 files changed