Check if /etc/rc.local exists before running sed.

Closes #667

install/hst-install-debian.sh

@@ -1377,7 +1377,7 @@ if [ "$named" = 'yes' ]; then
     check_result $? "bind9 start failed"
 
     # Workaround for OpenVZ/Virtuozzo
-    if [ -e "/proc/vz/veinfo" ]; then
+    if [ -e "/proc/vz/veinfo" ] && [ -e "/etc/rc.local" ]; then
         sed -i "s/^exit 0/service bind9 restart\nexit 0/" /etc/rc.local
     fi
 fi

install/hst-install-ubuntu.sh

@@ -1354,7 +1354,7 @@ if [ "$named" = 'yes' ]; then
     check_result $? "bind9 start failed"
 
     # Workaround for OpenVZ/Virtuozzo
-    if [ -e "/proc/vz/veinfo" ]; then
+    if [ -e "/proc/vz/veinfo" ] && [ -e "/etc/rc.local" ]; then
         sed -i "s/^exit 0/service bind9 restart\nexit 0/" /etc/rc.local
     fi
 fi