Fix up export permission checking

Order access list checking such that Root_Access does not
grant read/write access. A separate access must grant
some access. If no other access list grants any access,
read access will be granted though.

The access list checking is more unified so the same logic is
used for both IPv4 and IPv6 clients.

nfs_export_check_access now returns the export permission options
that apply to the client. This makes it easier to do proper permission
checking

This rework will make it much easier to implement the EXPORT_CLIENT
stanza that allows more per client permissions.

Remove some more vestiges of NFSv2 support because we need the
EXPORT_OPTION_NFSV2 bit.

Ported from 1.5.x 0ec84704627133b7138bf6299cf1c7b406fd70b0

Signed-off-by: Frank Filz <ffilz@us.ibm.com>

Conflicts:

	src/MainNFSD/nfs_stat_exporter_thread.c
	src/MainNFSD/nfs_worker_thread.c
	src/Protocols/NFS/nfs4_Compound.c
	src/Protocols/NFS/nfs_Read.c
	src/Protocols/NFS/nfs_Write.c
	src/Protocols/NFS/nfs_proto_tools.c
	src/include/nfs_core.h
	src/include/nfs_exports.h
	src/support/exports.c
	src/support/nfs_export_list.c