Lock-free memory allocator

Release builds will now use lock-free allocator by
default without any internal locks happening.

MemHead is also reduces to as minimum as it's possible.
It still need to be size_t stored in a MemHead in order
to make us keep track on memory we're requesting from
the system, not memory which system is allocating. This
is probably also faster than using a malloc's usable
size function.

Lock-free guarded allocator will say you whether all
the blocks were freed, but wouldn't give you a list
of unfreed blocks list. To have such a list use a
--debug or --debug-memory command line arguments.

Debug builds does have the same behavior as release
builds. This is so tools like valgrind are not
screwed up by guarded allocator as they're currently
are.

--
svn merge -r59941:59942 -r60072:60073 -r60093:60094 \
          -r60095:60096 ^/branches/soc-2013-depsgraph_mt

CMakeLists.txt

@@ -287,9 +287,6 @@ mark_as_advanced(WITH_MEM_VALGRIND)
 option(WITH_CXX_GUARDEDALLOC "Enable GuardedAlloc for C++ memory allocation tracking (only enable for development)" OFF)
 mark_as_advanced(WITH_CXX_GUARDEDALLOC)
 
-option(WITH_GUARDEDALLOC "Enable GuardedAlloc (DISABLE AT OWN RISK!)" ON)
-mark_as_advanced(WITH_GUARDEDALLOC)
-
 option(WITH_ASSERT_ABORT "Call abort() when raising an assertion through BLI_assert()" OFF)
 mark_as_advanced(WITH_ASSERT_ABORT)