krb5_child: Increase child buffer and chunk size

Port
9869e48
to sssd-2-8

Passkey data can be larger than 512 bytes.

Received passkey data from krb5 with multiple credentials
exceeds 256 bytes.

Reviewed-by: Iker Pedrosa <ipedrosa@redhat.com>
Reviewed-by: Sumit Bose <sbose@redhat.com>

src/util/child_common.h

@@ -32,8 +32,8 @@
 
 #include "util/util.h"
 
-#define IN_BUF_SIZE         512
-#define CHILD_MSG_CHUNK     256
+#define IN_BUF_SIZE         2048
+#define CHILD_MSG_CHUNK     1024
 
 #define SIGTERM_TO_SIGKILL_TIME 2