[PATCH] malloc: Remove __malloc_initialize_hook from the API [BZ #19564]

[DJ Delorie]

Is there any way we could mark this in the ABI itself so that attempts
to link against obsolete hooks only work if you've selected an older
ABI, but fail with a suitable warning if you link against a new ABI?  It
looks like a recompile would be needed to provide backwards
compatibility.  (assuming we want to provide this feature at all, but is
a link-warning-free-but-doesnt-do-anything solution better than "old
apps don't build" ?)

The new malloc-hooks.h doesn't match the poison list in stdc-predef.h.
I assume that's "not yet" but the patch should be internally consistent.