For sam_challenge do not encode optional strings if string not present.
Previously, a string of length zero was transmitted.


To generate a diff of this commit:



	cvs diff -r5.130 -r5.131 krb5/src/lib/krb5/asn.1/ChangeLog
	cvs diff -r5.27 -r5.28 krb5/src/lib/krb5/asn.1/asn1_k_encode.c
	cvs diff -r1.70 -r1.71 krb5/src/tests/asn.1/ChangeLog
	cvs diff -r1.26 -r1.27 krb5/src/tests/asn.1/krb5_decode_test.c
	cvs diff -r1.8 -r1.9 krb5/src/tests/asn.1/reference_encode.out
	cvs diff -r1.10 -r1.11 krb5/src/tests/asn.1/trval_reference.out