GitLab

* replace ccache with sccache, pin package versions

* put ccache back temporarily to avoid breaking other CI jobs

* add sccashe_wrapper.sh script

* fix the package version syntax

* fix the pymysql package issue

* run sccache_wrapper before build if ccache server found

* set the paths before calling the sccache_wrapper

* use /tmp instead of /usr/local for cache

* try using sccache --start-server instead of wrapper

* try using redis server with sccache

* define SCCACHE_REDIS

* add redis and ping packages, and redis port

* use the new sccache redis server

* do not use sccache with staging compiler

* fix the condition syntax

* add stunnel to redis

* add tunnel verification

* separate caches for different architectures

* fix syntax for the cache tag

* quse double brackets for conditions

* add bash line to the script

* add a switch for sccache and only use it in build stage

* run check_host fun...