(toplevel) [SYSTEM_MALLOC || DOUG_LEA_MALLOC]: Undef

(toplevel) [SYSTEM_MALLOC || DOUG_LEA_MALLOC]: Undef
GC_MALLOC_CHECK.
(toplevel) [GC_MARK_STACK || GC_MALLOC_CHECK]: Move mem_node
structure definition and related variabled to the top of the file.
Include this code when GC_MALLOC_CHECK is defined.
(lisp_malloc, lisp_free) [GC_MALLOC_CHECK]: Don't
register/unregister allocated region.
(emacs_blocked_free) [GC_MALLOC_CHECK]: Check if freeing something
which isn't allocated.
(emacs_blocked_malloc) [GC_MALLOC_CHECK]: Check if returning
something which is already in use.
(emacs_blocked_realloc) [GC_MALLOC_CHECK]: Likewise.
(mem_insert) [GC_MALLOC_CHECK]: Use _malloc_internal.
(mem_delete) [GC_MALLOC_CHECK]: Use _free_internal.
(init_alloc_once) [GC_MALLOC_CHECK]: Call mem_init.