envsetup: Split cached vars

function destroy_build_var_cache()

{

    unset BUILD_VAR_CACHE_READY

    for v in $cached_vars; do

    for v in $(echo $cached_vars | tr " " "\n"); do

      unset var_cache_$v

    done

    unset cached_vars

    for v in $cached_abs_vars; do

    for v in $(echo $cached_abs_vars | tr " " "\n"); do

      unset abs_var_cache_$v

    done

    unset cached_abs_vars