Save detailed error messages (usually from the krb5 library) in
per-thread storage, mapping each error code to the most recently
produced message for it.  Return the message from display_status.

Currently not implemented for a few cases where the krb5 mechanism
returns a minor status code of 0, or another value different from the
libkrb5 error code.

Other functions are available to store a generic string or formatted
message, but aren't used much at present.

Tested with these errors in context establishment:
 * missing ccache (libkrb5 shows pathname if FILE: type)
 * missing keytab (libkrb5 shows pathname if FILE: type)
 * server principal unknown (libkrb5 shows server principal)

Commit By: raeburn



Revision: 19672
Changed Files:
U   trunk/src/lib/gssapi/gss_libinit.c
U   trunk/src/lib/gssapi/krb5/Makefile.in
U   trunk/src/lib/gssapi/krb5/accept_sec_context.c
U   trunk/src/lib/gssapi/krb5/acquire_cred.c
U   trunk/src/lib/gssapi/krb5/add_cred.c
U   trunk/src/lib/gssapi/krb5/context_time.c
U   trunk/src/lib/gssapi/krb5/copy_ccache.c
U   trunk/src/lib/gssapi/krb5/delete_sec_context.c
U   trunk/src/lib/gssapi/krb5/disp_name.c
U   trunk/src/lib/gssapi/krb5/disp_status.c
U   trunk/src/lib/gssapi/krb5/duplicate_name.c
U   trunk/src/lib/gssapi/krb5/export_name.c
U   trunk/src/lib/gssapi/krb5/export_sec_context.c
U   trunk/src/lib/gssapi/krb5/gssapiP_krb5.h
U   trunk/src/lib/gssapi/krb5/gssapi_krb5.c
U   trunk/src/lib/gssapi/krb5/import_name.c
U   trunk/src/lib/gssapi/krb5/import_sec_context.c
U   trunk/src/lib/gssapi/krb5/init_sec_context.c
U   trunk/src/lib/gssapi/krb5/inq_context.c
U   trunk/src/lib/gssapi/krb5/inq_cred.c
U   trunk/src/lib/gssapi/krb5/k5seal.c
U   trunk/src/lib/gssapi/krb5/k5sealv3.c
U   trunk/src/lib/gssapi/krb5/k5unseal.c
U   trunk/src/lib/gssapi/krb5/rel_cred.c
U   trunk/src/lib/gssapi/krb5/val_cred.c