remove ser

openwrt/Config.in.devel

openwrt/package/ser/Config.in

openwrt/package/ser/Makefile

openwrt/package/ser/ipkg/ser.control

openwrt/package/ser/patches/100-sc.patch

openwrt/package/ser/patches/110-locking.patch

openwrt/package/ser/patches/120-main.patch

openwrt/package/ser/patches/200-no_libfl.patch

openwrt/package/ser/patches/210-runtime_paths.patch

openwrt/package/ser/patches/220-default_config.patch