Fix leaks in gss_inquire_cred_by_oid()

In the mechglue gss_inquire_cred_by_oid(), remove an unnecessary
allocation of ret_set which is overwritten by the first mechanism's
result.

(cherry picked from commit 0d39d46852587d36fcc5024d5766586faba9044a)

https://github.com/krb5/krb5/commit/c67c28858a557575e2a7a2811b235eb6d639a330
Author: Greg Hudson <ghudson@mit.edu>
Commit: c67c28858a557575e2a7a2811b235eb6d639a330
Branch: krb5-1.15
 src/lib/gssapi/mechglue/g_inq_cred_oid.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)