malloc: Optimize small memory clearing for calloc

Add calloc-clear-memory.h to clear memory size up to 36 bytes (72 bytes
on 64-bit targets) for calloc.  Use repeated stores with 1 branch, instead
of up to 3 branches.  On x86-64, it is faster than memset since calling
memset needs 1 indirect branch, 1 broadcast, and up to 4 branches.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

malloc/malloc-internal.h

@@ -23,6 +23,7 @@
 #include <malloc-sysdep.h>
 #include <malloc-size.h>
 #include <malloc-hugepages.h>
+#include <calloc-clear-memory.h>
 
 /* Called in the parent process before a fork.  */
 void __malloc_fork_lock_parent (void) attribute_hidden;