Add a DREP_LITTLE_ENDIAN for the DCE RPC endianness bit in the data

Add a DREP_LITTLE_ENDIAN for the DCE RPC endianness bit in the data
representation.  Use it rather than a raw 0x10.

Add a DREP_ENC_INTEGER() macro that takes a pointer to the data
representation and returns either ENC_LITTLE_ENDIAN or ENC_BIG_ENDIAN;
use it for the encoding argument to proto_tree_add_item(), rather than
just the AND of drep[0] and DREP_LITTLE_ENDIAN, as it's not a boolean
any more, and for string values we'll be supporting character encodings
as well and thus won't be able to trust that the 0x10 bit will mean
"little endian".

Use ENC_NA for some other encoding values, i.e. for FT_BYTES and the
like.

Fix a couple of places in the DCOM dissector where we were passing the
byte-order bit rather than the field value to
proto_tree_add_uint_format().

Clean up white space.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@38128 f5534014-38df-0310-8fa8-9805f1628bb7