需要 SLE 12 SP5 Backports ，用 root 執行：
zypper addrepo https://download.opensuse.org/repositories/home:ojkastl_buildservice:Backports_Apache_Modules/SLE_12_SP5_Backports/home:ojkastl_buildservice:Backports_Apache_Modules.repo
zypper refresh
zypper install apache2-mod_auth_gssapi