MDEV-5120 Test suite test maria-no-logging fails

stat structure (from <sys/stat.h>) is conditionally defined
to have different layout and size depending on the defined macros.
The correct macro is defined in my_config.h, which means it MUST be
included first (or, at least before <features.h> - so, practically,
before including any system headers).

storage/example/ha_example.cc

@@ -98,6 +98,7 @@
 #pragma implementation        // gcc: Class implementation
 #endif
 
+#include <my_config.h>
 #include <mysql/plugin.h>
 #include "ha_example.h"
 #include "sql_class.h"