Some small fixes to our charset conversion code:

Some small fixes to our charset conversion code:

 - Treat the NMB names in the 'session request' packet as 'ASCII'.  This means
   that we do not get invalid multibyte from the wire, even if we truncate
   in the conversion.  (Otherwise we panic when we try to strupper_m it).

 - Remove acnv_uxu2(), as it was duplicated by push_ucs2_allocate()
 - Remove acnv_dosu2(), as it is not used.

 - In push_ucs2(), with the STR_UPPER flag, do the case conversion *after*
   the UCS2 conversion, when it we know that the length can't change.  Also
   faster, as we don't need to do another 2 UCS2 conversions.

Andrew Bartlett
(This used to be commit 912035af1178424583d0bf887a391a0cac2acd87)