fix strange garbage results

needs to be reviewed by maintainers

Author: thehesiod

libsrc/memio.c

@@ -382,8 +382,9 @@ fprintf(stderr,"memio_open: initial memory: %lu/%lu\n",(unsigned long)memio->mem
         (void)close(fd);
     }
 
-    /* Use half the filesize as the blocksize ; why? */
-    sizehint = filesize/2;
+    /* Return 8192 as large values cause: https://github.com/Unidata/netcdf-c/issues/401 Why? 
+     Note: File modes use: blksize(fd); */
+    sizehint = 8192;
 
     fd = nc__pseudofd();
     *((int* )&nciop->fd) = fd;