functions: make __pids_var_run() dash compliant

Signed-off-by: Davide Madrisan <davide.madrisan@gmail.com>

etc/rc.d/init.d/functions

@@ -95,9 +95,12 @@ __pids_var_run ()
    pid=
    if [ -f "$pid_file" ] ; then
       local line p
+      [ -r "$pid_file" ] || return 4 # "user had insufficient privilege"
       read line < "$pid_file"
       for p in $line ; do
-         [ -z "${p//[0-9]/}" -a -d "/proc/$p" ] && pid="$pid $p"
+         case $p in *[!0-9]*) : ;;
+            *) [ -d "/proc/$p" ] && pid="$pid $p" ;;
+         esac
       done
       if [ -n "$pid" ]; then
          return 0