try to seek again

this still fails.

Author: kain88-de

package/MDAnalysis/lib/formats/xdrlib.pxd

@@ -7,7 +7,7 @@ cdef extern from 'include/xdrfile.h':
 
     XDRFILE* xdrfile_open (char * path, char * mode)
     int xdrfile_close (XDRFILE * xfp)
-    xdr_seek(XDRFILE *xfp, int pos, int whence)
+    xdr_seek(XDRFILE *xfp, int64_t pos, int whence)
     ctypedef float matrix[3][3]
     ctypedef float rvec[3]