Fix a memory leak in make_gss_checksum.

From greg.mcclement@sap.com.

https://github.com/krb5/krb5/commit/a642f23fe7988a13625e97067d52b92f8ddf9544
Commit By: ghudson
Revision: 25323
Changed Files:
U   trunk/src/lib/gssapi/krb5/init_sec_context.c