calloc: Make sure we always have an overflow-checking calloc() available

This tries to make sure that everywhere in this source tree, we always have
an appropriate version of calloc() (i.e. grub_calloc(), xcalloc(), etc.)
available, and that they all safely check for overflow and return NULL when
it would occur.

Signed-off-by: Peter Jones <pjones@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/kern/emu/misc.c

@@ -85,6 +85,18 @@ grub_util_error (const char *fmt, ...)
   exit (1);
 }
 
+void *
+xcalloc (grub_size_t nmemb, grub_size_t size)
+{
+  void *p;
+
+  p = calloc (nmemb, size);
+  if (!p)
+    grub_util_error ("%s", _("out of memory"));
+
+  return p;
+}
+
 void *
 xmalloc (grub_size_t size)
 {