miext: replace xallocarray() by calloc()

Only key difference that calloc(), in contrast to rellocarray(),
is zero-initializing. The overhead is hard to measure on today's
machines, and it's safer programming practise to always allocate
zero-initialized, so one can't forget to do it explicitly.

Cocci rule:

    @@
    expression COUNT;
    expression LEN;
    @@
    - xallocarray(COUNT,LEN)
    + calloc(COUNT,LEN)

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

miext/damage/damage.c

@@ -1318,7 +1318,7 @@ damageText(DrawablePtr pDrawable,
     if (!checkGCDamage(pDrawable, pGC))
         return;
 
-    charinfo = xallocarray(count, sizeof(CharInfoPtr));
+    charinfo = calloc(count, sizeof(CharInfoPtr));
     if (!charinfo)
         return;