use g_mem_chunk_alloc0() to allocate the memchunk, so the correct size of

use g_mem_chunk_alloc0() to allocate the memchunk, so the correct size of

Sat Sep  5 04:40:02 1998  Tim Janik  <timj@gtk.org>

        * glib.h:
        (g_chunk_new0): use g_mem_chunk_alloc0() to allocate the memchunk,
        so the correct size of the memchunk is allocated with 0's and not
        a memory portion of the size of the desired type.

        * gmem.c: new function g_mem_chunk_alloc0() which will initialize
        a memory area allocated with g_mem_chunk_alloc() with 0's.