[package] [splash-osmc] make clean should delete src/
[package] common.sh: add function to configure build environment network capabilities; use dpkg -s not dpkg -l for valid way of verifying if a package is installed in handle_dep and fix chroot operations of build_in_env to preserve OSMC sourced function environment
[package] [splash-osmc] Depends: fbset should be set at build time as fix_arch_ctl will remove otherwise; add libpng12-dev dependency; make sure we exit Makefile gracefully and don't fail the build to break recursion; umount tc/mnt after build