src/: Use xasprintf() instead of its pattern

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/obscure.c

@@ -21,6 +21,7 @@
 #include "prototypes.h"
 #include "defines.h"
 #include "getdef.h"
+#include "string/sprintf/xasprintf.h"
 
 #if WITH_LIBBSD == 0
 #include "freezero.h"
@@ -99,9 +100,7 @@ static /*@observer@*//*@null@*/const char *password_check (
 
 	newmono = str_lower (xstrdup (new));
 	oldmono = str_lower (xstrdup (old));
-	wrapped = XMALLOC(strlen(oldmono) * 2 + 1, char);
-	strcpy (wrapped, oldmono);
-	strcat (wrapped, oldmono);
+	xasprintf(&wrapped, "%s%s", oldmono, oldmono);
 
 	if (palindrome (oldmono, newmono)) {
 		msg = _("a palindrome");