Utility functions to move allocations from k5buf/krb5_data to gss_buffer_t

Utility functions to move allocations from k5buf/krb5_data to gss_buffer_t

On Unix, these simply move the buffer pointer, but on windows they need to
reallocated with gssalloc_malloc and coied since the gss_buffer_t may need
to be freed in a separate module with potentially mismatched c runtime.

Also fix a mismatched parameter warning in generic_gss_copy_oid_set().

Signed-off-by: Kevin Wasserman <kevin.wasserman@painless-security.com>
git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@25331 dc483132-0cff-0310-8789-dd5450dbe970