gfs-kernel: Workaround fix for bz 444912 (gfs_glock_is_locked_by_me problem)
    
    This one-line fix, removes the assert warning. The behavior of the code is unchanged except that the assert warnings will no longer appear in the logs. This warning is tripped through the madvise syscall where control reaches the readpage function without the inode glock being held. We return -ENOSYS in such a case, disabling the madvise syscall.
    
    A more elegant fix for RHEL5 gfs that supports the madvise syscall (bz 429343) could not be ported to RHEL4 because AOP_TRUNCATED_PAGE is not available in RHEL4.