ARC: MWDT: LIB: implement ___errno hook

Implement ___errno so ARC MWDT libc can use proper (Zephyr) errno

Signed-off-by: Eugeniy Paltsev <[email protected]>
Signed-off-by: Evgeniy Paltsev <[email protected]>

Author: evgeniy-paltsev

lib/libc/arcmwdt/libc-hooks.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2015, 2021 Intel Corporation.
+ * Copyright (c) 2021 Synopsys.
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -56,3 +57,8 @@ int _write(int fd, const char *buf, unsigned int nbytes)
 	return z_impl_zephyr_write_stdout(buf, nbytes);
 }
 #endif
+
+int *___errno(void)
+{
+	return z_errno();
+}