* gc-malloc.c, gc.h (scm_gc_malloc_prehistory): New function.

* gc-malloc.c, gc.h (scm_gc_malloc_prehistory): New function.

* gc-malloc.c (malloc_mutex): New mutex.
(scm_gc_malloc_prehistory): Initialize it.
(scm_realloc): Serialize call to realloc
(scm_calloc): Same for calloc.
Thanks to Wolfgang Jaehrling!
(Now we have to make sure all calls to malloc/realloc are made
through scm_malloc.)

* init.c (scm_init_guile_1): Call scm_gc_malloc_prehistory.