gssd: Add support for the new upcall required by commit 428879dc9110

Commit 428879dc9110 adds a requirement for a new upcall for the
gssd(8). This patch adds that upcall.

Unfortunately, the old gssd.c would not build against the new
patched gssd.x.

This patch will fix the build.

(cherry picked from commit 82ea0132c8b17a7a6067c8a36c6434e587ede6de)