This change reduces the number of calls to dlsym() when loading tools from a
lot to one.  This required two basic changes.

1. Tools are responsible for telling the tool about any functions they
provide that the tool may call.  This includes basic functions like
TL_(instrument)(), functions that assist core services such as
TL_(pp_Error)(), and malloc-replacement-related functions like
TL_(malloc)().  

2. Tools that replace malloc now specify the size of the heap block redzones
through an arg to the VG_(malloc_funcs)() function, rather than with a
variable VG_(vg_malloc_redzone_szB).

One consequence of these changes is that VG_(tool_init_dlsym)() no longer
needs to be generated by gen_toolint.pl.

There are a number of further improvements that could follow on from this one.
- Avoid the confusingly different definitions of the TL_() macro in the
  core vs. for tools.  Indeed, the functions provided by the tools now don't
  need to use the TL_() macro at all, as they can have arbitrary names.
- Remove a lot of the auto-generated stuff in vg_toolint.c and vg_toolint.h
  (indeed, it might be possible to not auto-generate these at all, which
  would be nice).
- The handling of VgToolInterface is currently split across vg_needs.c and
  vg_toolint.c, which isn't nice.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@3487 a5019735-40e9-0310-863c-91ae7b9d1cf9
17 files changed