Suppress "packed member" warning

Marlin/src/sd/SdBaseFile.cpp

  *
  */
 
+#if __GNUC__ > 8
+  // The NXP platform updated GCC from 7.2.1 to 9.2.1
+  // and this new warning apparently can be ignored.
+  #pragma GCC diagnostic ignored "-Waddress-of-packed-member"
+#endif
+
 /**
  * Arduino SdFat Library
  * Copyright (c) 2009 by William Greiman