For review: GSS memory allocation patches

[Kevin Wasserman]

I've pushed updated versions of these patches to Sam's github repository
(rebased off mit trunk as of this afternoon).  These should address the
concerns raised by Greg as well as properly handling out-of-memory
conditions, gss_OID_set memory usage and GSS_C_DCE_STYLE.

Simplify gss_indicate_mechs() by using generic_gss_copy_oid_set
https://github.com/hartmans/kfw-updates/commit/5b8ce7277fbe87278155a69e30ffe96f14dd155e
Add new public header gssapi_alloc.h (added gssalloc_calloc; fixed to use 
strlcpy instead of strcpy)
https://github.com/hartmans/kfw-updates/commit/091b140c2005e178de4d3d26afab829a39cad405
Utility functions to move allocations from k5buf/krb5_data to gss_buffer_t
https://github.com/hartmans/kfw-updates/commit/f5372211c124317ee7824702d002f6b5f68149c5
Use gssalloc memory management where appropriate
https://github.com/hartmans/kfw-updates/commit/b17c2e27aec70e2edeeea3d28c89f070b681d2ae
Add "-dce" commandline option to gss-client.c to set GSS_C_DCE_STYLE flag
https://github.com/hartmans/kfw-updates/commit/42a6344bb0074cf939b71f3fcac4dc49403af515