TAKE - fix mtime updates in the 2.5 kernel

[Steve Lord <lord@xxxxxxx>]

optimize timestamp updates, use new hires timestamps more directly,
also fix a bug where the mtime field was not correctly updated.


Date:  Thu Mar 20 18:50:03 PST 2003
Workarea:  jen.americas.sgi.com:/src/lord/xfs-merge.2.5

The following file(s) were checked into:
  bonnie.engr.sgi.com:/isms/slinx/2.5.x-xfs


Modid:  2.5.x-xfs:slinx:142296a
linux/fs/xfs/xfs_inode.c - 1.366
        - cleanup xfs_ichgtime, fix assignment of mtime

linux/fs/xfs/linux/xfs_vnode.c - 1.112
        - use direct assignment between timeval structures, reduce cost
          of the getattr call.

linux/fs/xfs/support/time.h - 1.12
        - use CURRENT_TIME to implement nanotime