ndr: fix push/pull DATA_BLOB with NDR_NOALIGN

ndr: fix push/pull DATA_BLOB with NDR_NOALIGN

This change addresses bug 9026.
There are 3 use cases for DATA_BLOB marshalling/unmarshalling:

1)
ndr_push_DATA_BLOB and ndr_pull_DATA_BLOB when called with
LIBNDR_FLAG_ALIGN* alignment flags set, are used to push/pull padding
bytes _only_. The length is determined by the alignment required and
the current ndr offset.
e.g. dcerpc.idl:
        typedef struct {
...
                [flag(NDR_ALIGN8)]    DATA_BLOB _pad;
        } dcerpc_request;

2)
When called with the LIBNDR_FLAG_REMAINING flag, all remaining bytes in
the ndr buffer are pushed/pulled.
e.g. dcerpc.idl:
        typedef struct {
...
                [flag(NDR_REMAINING)] DATA_BLOB stub_and_verifier;
        } dcerpc_request;

3)
When called without alignment flags, push/pull a uint32 length _and_ a
corresponding byte array to/from the ndr buffer.
e.g. drsblobs.idl
        typedef [public] struct {
...
                DATA_BLOB data;
        } DsCompressedChunk;

The fix for bug 8373 changed the definition of "alignment flags", such
that when called with LIBNDR_FLAG_NOALIGN ndr_push/pull_DATA_BLOB
behaves as (1: padding bytes) rather than (3: uint32 length + byte
array).

This breaks marshalling/unmarshalling for the following structures.
eventlog.idl:
        typedef [flag(NDR_NOALIGN|NDR_PAHEX),public] struct {
...
                DATA_BLOB sid;
...
        } eventlog_Record_tdb;

ntprinting.idl:
        typedef [flag(NDR_NOALIGN),public] struct {
...
                DATA_BLOB *nt_dev_private;
        } ntprinting_devicemode;

        typedef [flag(NDR_NOALIGN),public] struct {
...
                DATA_BLOB data;
        } ntprinting_printer_data;

Signed-off-by: Günther Deschner <gd@samba.org>
(cherry picked from commit 0d3249b927465fdca1765cbd7e17c947364b5ef0)