Use &error_fatal when initializing crypto on qemu-{img,io,nbd}

In addition to making the code simpler, this will replace the
long error messages:
  cannot initialize crypto: Unable to initialize GNUTLS library: [...]
  cannot initialize crypto: Unable to initialize gcrypt
with shorter messages:
  Unable to initialize GNUTLS library: [...]
  Unable to initialize gcrypt

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
diff --git a/qemu-io.c b/qemu-io.c
index 5ef3ef7..d977a6e 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -466,10 +466,7 @@
     progname = basename(argv[0]);
     qemu_init_exec_dir(argv[0]);
 
-    if (qcrypto_init(&local_error) < 0) {
-        error_reportf_err(local_error, "cannot initialize crypto: ");
-        exit(1);
-    }
+    qcrypto_init(&error_fatal);
 
     module_call_init(MODULE_INIT_QOM);
     qemu_add_opts(&qemu_object_opts);