st_rdev in struct stat is being access without any regards to HAVE_RDEV in the following files:

ext/standard/filestat.c
ext/standard/file.c

file.c has the following code:

#ifdef HAVE_ST_BLKSIZE
	add_assoc_long ( return_value, "rdev" , stat_sb.st_rdev );
	add_assoc_long ( return_value , "blksize" , stat_sb.st_blksize );
#endif

and filestat.c has the following code:

#ifdef HAVE_ST_BLKSIZE
		add_next_index_long(return_value, stat_sb->st_rdev);
#else
		add_next_index_long(return_value, -1);
#endif

in both cases, it should have been checking for HAVE_ST_RDEV before accessing the st_rdev field.