tests/kernel/common: Include errno_private.h

This ensures that we have a definition of z_errno in case
that isn't pulled in with errno.h

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

tests/kernel/common/src/errno.c

@@ -7,6 +7,7 @@
 #include <ztest.h>
 #include <zephyr/zephyr.h>
 #include <errno.h>
+#include <zephyr/sys/errno_private.h>
 
 /**
  * @brief Test the thread context