Add preprocessor directive __attribute__((packed)) to cromfs_node_s

This directive tells the compiler that cromfs_node_s might be located at a memory
address which is not word aligned. This resolves the hardFault caused by unaligned
memory access on armv6-m architecture which doesn't support it.

fs/cromfs/cromfs.h

@@ -102,7 +102,7 @@ struct cromfs_volume_s
  *                Return 0
  */
 
-struct cromfs_node_s
+begin_packed_struct struct cromfs_node_s
 {
   uint16_t cn_mode; /* File type, attributes, and access mode bits */
   uint16_t cn_pad;  /* Not used */
@@ -116,6 +116,6 @@ struct cromfs_node_s
     uint32_t cn_link;   /* Offset to an arbitrary node (for hard link) */
     uint32_t cn_blocks; /* Offset to first block of compressed data (for read) */
   } u;
-};
+} end_packed_struct;    /* Use packed access since cromfs nodes may be unaligned */
 
 #endif /* __FS_CROMFS_CROMFS_H */