gssapi: Add error checks and cleanup the code in ssh_gssapi_auth_mic().
gssapi: Add error checks and cleanup the code in ssh_gssapi_auth_mic().

Distrotech/libssh,wangshawn/libssh,sebadoom/libssh,DouglasHeriot/libssh,DouglasHeriot/libssh,pouete/libssh,sebadoom/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh,robxu9/libssh,mwgoldsmith/ssh,pouete/libssh,kedazo/libssh,sebadoom/libssh,Distrotech/libssh,taikoo/libssh,kedazo/libssh,Distrotech/libssh,pouete/libssh,pouete/libssh,robxu9/libssh,elastichosts/libssh,taikoo/libssh,Distrotech/libssh,nviennot/libssh,DouglasHeriot/libssh,mwgoldsmith/libssh,wangshawn/libssh,taikoo/libssh,sebadoom/libssh,nviennot/libssh,nviennot/libssh,mwgoldsmith/ssh,kedazo/libssh,mwgoldsmith/libssh,robxu9/libssh,mwgoldsmith/ssh,robxu9/libssh,wangshawn/libssh,taikoo/libssh,nviennot/libssh,elastichosts/libssh,mwgoldsmith/libssh,DouglasHeriot/libssh,wangshawn/libssh,elastichosts/libssh,kedazo/libssh