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>

src/login.c

@@ -22,6 +22,8 @@
 #include <sys/stat.h>
 #include <sys/ioctl.h>
 #include <assert.h>
+
+#include "alloc.h"
 #include "defines.h"
 #include "faillog.h"
 #include "failure.h"
@@ -589,7 +591,7 @@ int main (int argc, char **argv)
 #ifdef RLOGIN
 	if (rflg) {
 		assert (NULL == username);
-		username = xmalloc (USER_NAME_MAX_LENGTH + 1);
+		username = XMALLOCARRAY (USER_NAME_MAX_LENGTH + 1, char);
 		username[USER_NAME_MAX_LENGTH] = '\0';
 		if (do_rlogin (hostname, username, USER_NAME_MAX_LENGTH, term, sizeof term)) {
 			preauth_flag = true;
@@ -906,7 +908,7 @@ int main (int argc, char **argv)
 				exit (1);
 			}
 			preauth_flag = false;
-			username = xmalloc (USER_NAME_MAX_LENGTH + 1);
+			username = XMALLOCARRAY (USER_NAME_MAX_LENGTH + 1, char);
 			username[USER_NAME_MAX_LENGTH] = '\0';
 			login_prompt (_("\n%s login: "), username, USER_NAME_MAX_LENGTH);