Use safer allocation macros

Use of these macros, apart from the benefits mentioned in the commit
that adds the macros, has some other good side effects:

-  Consistency in getting the size of the object from sizeof(type),
   instead of a mix of sizeof(type) sometimes and sizeof(*p) other
   times.

-  More readable code: no casts, and no sizeof(), so also shorter lines
   that we don't need to cut.

-  Consistency in using array allocation calls for allocations of arrays
   of objects, even when the object size is 1.

Cc: Valentin V. Bartenev <vbartenev@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

libmisc/mail.c

@@ -15,6 +15,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "alloc.h"
 #include "getdef.h"
 
 #ident "$Id$"
@@ -38,7 +39,7 @@ void mailcheck (void)
 		size_t len = strlen (mailbox) + 5;
 		int wlen;
 
-		newmail = xmalloc (len);
+		newmail = XMALLOCARRAY (len, char);
 		wlen = snprintf (newmail, len, "%s/new", mailbox);
 		assert (wlen == (int) len - 1);