Fix build on kernel versions 2.6.36 to 3.5.0

clear_inode() was renamed to end_writeback() in kernel version 2.6.36. It was then renamed back to clear_inode in version 3.5.0. This commit fixes builds on those kernels which also happen to be used by a large majority of android devices at present.

I have tested this on 3.4.0 and 3.5.0.