build.sh: add option to "patch" to prevent creating backup files. those backup files must not be included in rootfs of firmware because those can cause unexpected runtime issues. for instance I had a problem where backuped files are stored under /etc/board.d/. those files are executed and had created invalid /etc/config/network for some devices with switches

DL/WORKDIR

gitlab: add FF_GITLAB_REMOVE_WORKDIR and FF_GITLAB_REMOVE_DL to control whether those directories should be deleted in init-step or not. This helps to optimize build process in nightly builds.

gitlab: add FF_GITLAB_REMOVE_WORKDIR and FF_GITLAB_REMOVE_DL to control whether those directories should be deleted in init-step or not. This helps to optimize build process in nightly builds.

fix wifi 5ghz check: # Use ch 11 which is present for all countries. (nanostation has no 12+13 during boot)