Branch: b1_4

Branch: b1_4
Allow NFSD to reopen files for write that were created without write perms.
This is needed for HPUX NFS clients (cp creates files with mode 000), and
Linux NFS test progs that intentionally do the same because NFSD always
reopens files for each client RPC and loses the Lustre initial open(O_CREAT)
file handle that was allowed to open-for-write a readonly file.
This only works for the file owner so it is no net loss of security (the
user could always just chmod a file and then write to it).  Tested at HP.
b=5781
r=peter (concept)