rfc3961: Use enctypes, not keytypes

We previously defined the enctype symbols to be aliases for keytype
symbols.  The numerical values matched what we wanted (since these
values are specified in an IANA registry), but the C type is not
required to be the same for enctypes and keytypes.

Some of our buildslave configurations notice the type mismatch and
complain, so fix the types by using the enctype enum for enctype symbols
instead of keytypes.

Change-Id: I56ca634d52954ee44baa34e2d8c876271f171288
Reviewed-on: http://gerrit.openafs.org/10693
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: Benjamin Kaduk <kaduk@mit.edu>
afs_fetchstore: avoid use of uninitialized variable

rxfs_fetchInit() attempts to do a 64-bit RPC first, but falls back
to the 32-bit StartRXAFS_FetchData() if the server appears to not
support the 64-bit RPCs.

We correctly did not read a length from the call if the FetchData
RPC(s) failed, but proceeded to assign from the 'length' local
variable into the 'alength' output variable unconditionally later on.

Instead of blindly continuing on, jump to the error-handling part of
the routine when we cannot read a length from the call.  This has the
side effect of skipping an afs_Trace3() point in the error case.

Change-Id: I4840d5c692c61630c68e97b5e88f9460abade19e
Reviewed-on: http://gerrit.openafs.org/10694
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: Benjamin Kaduk <kaduk@mit.edu>