netsnmp: fix tab/space formatting in init.d script

The S59snmpd script has a strange mix of tabs and spaces.  Replace
tabs with spaces, and also remove unnecessary line continuations
from the start-stop-daemon lines, as none of them go beyond 80
columns.

Signed-off-by: Danomi Manchego <danomimanchego123@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>